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Tesi sul tema "Organic compounds Synthesis"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 30 luglio 2024

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1

Newington, Ian M. "Azo-anions in organic synthesis". Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:690ab891-be13-4582-a029-47974d20adac.

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Novel synthetic applications of ambident azo-anions derived from hindered hydrazones have been investigated. Reaction with electrophiles occurred predominantly at carbon as the N-addition pathway was sterically retarded. Trityl, diphenyl-4-pyridylmethyl (DPP) benzhydryl, and t-butyldiphenylmethyl (BDP) hydrazones of various aldehydes and ketones were prepared in good yields from the corresponding hydrazines and carbonyls in aqueous methanol. The lithium salts derived from trityl and DPP hydrazones, by treatment with methyl lithium at -55°C, reacted with aldehydes and ketones to generate azo-alkoxides. These could be diverted to alcohols,by sequential protonation and spontaneous homolysis (about -20°C) in the presence of ethanethiol, or to alkenes,by treatment with phosphorus trichloride at -78 G followed by azo-homolysis. The reactions enabled efficient reductive cross-coupling of aldehydes and ketones. The mechanism of the alkene forming reaction was investigated. Anions of benzhydryl hydrazones were found to react inefficiently by a G-addition pathway giving mainly N-addition products. Anions of BDP hydrazones conveniently gave excellent yields of azo-alkanes upon treatment with alkyl halides,but no products were obtained on reaction with carbonyl electrophiles. The azo-alkanes could be isolated and purified and acted as key intermediates for several synthetically useful transformations. Homolysis in refluxing benzene with thiophenol gave alkanes in good yields. Phenylselenenyl-, bromo-, and chloro-alkanes,and β-alkylstyrenes were generated when thiol was replaced by diphenyl diselenide, N-bromosuccinimide, N-chlorosuccinimide and β-nitrostyrene respectively. Treatment of the azo-alkanes with trifluoroacetic acid generated benzophenone alkylhydrazones. These were dissolved in ethanol with concentrated hydrochloric acid, thereafter hydrolysis yielded alkylhydrazines or treatment with hydrogen (1 atm., 50°C, 20h) over 10% Pd/C generated primary amines by a novel use of carbonyls as α-aminocarbanion equivalents.

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2

Esfandiarfard, Keyhan. "Novel Organophosphorus Compounds for Materials and Organic Synthesis". Doctoral thesis, Uppsala universitet, Molekylär biomimetik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-328295.

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This thesis is devoted to the development of new organophosphorus compounds for potential uses in material science and as reagents in Organic Chemistry. Organophosphorus compounds in a single molecule or organic electronics context are appealing as the phosphorous centers perturb the electronic properties of the π-conjugated systems while at the same time provide synthetic handles for subsequent synthetic modifications. As such, new synthetic methodology to such compounds and the exploration of new building blocks is of considerable interest. In a different study, novel organophosphorus compounds are synthesized and shown to promote a reaction in Organic Chemistry that has previously not been possible, i.e. the stereoselective reductive coupling of aldehydes to alkenes. Such developments enlarge the toolkit of reactions that are available to Organic Chemists, and may impact the synthetic routes to pharmaceuticals and other important commodity chemicals. A general introduction of the key structural unit of this thesis, phosphaalkenes, is given in the first chapter. The synthesis, reactivity, properties and applications of these P=C double bond containing compounds are highlighted. The Wittig reaction and its variations as well as the phosphorus analogues that produce phosphaalkenes are outlined in detail. The second chapter is dedicated to the synthesis of a precursor that is used for the preparation of novel π-conjugated, organophosphorus compounds. C,C-Dibromophosphaalkenes are prepared and the halide substituents are used for the selective introduction of acetylene units. Besides the phosphaalkenes, the successful syntheses of two new diphosphenes is presented, indicating a broad applicability of the precursors. The third chapter is dedicated to the isolation of a metal-free phosphanylphosphonate that transforms aldehydes quantitatively to their corresponding E-phosphaalkenes in a transition metal-free phospha-HWE (Horner-Wadsworth-Emmons) reaction. The reaction benefits from mild conditions, high E-stereoselectivity, and a broad substrate scope. In the last chapter, a novel method for the reductive coupling of aldehydes to olefins is introduced. The reaction, which is a vast improvement over the McMurry coupling, allows for the selective synthesis of symmetrical and most importantly unsymmetrical E-alkenes. The phosphanylphosphonate mentioned above is the reagent that facilitates the coupling of the aldehydes via a phosphaalkene intermediate. This one-pot reaction benefits from mild conditions, good conversions, and high E-stereoselectivity. In summary, the thesis presents novel aspects of organophosphorus chemistry. These include the preparations and exploration of interesting precursors for the construction of π-conjugated organophosphorus compounds, and the use of organophosphorus reagents for unprecedented transformations in Organic Chemistry.

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3

Reynolds, Stephen J. "Carbamoylcobalt (III) compounds in organic synthesis". Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280294.

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This thesis describes the development and use of organocobalt (III) compounds in the formation of carbon-carbon and carbon-heteroatom bonds and, in particular, details the application of this chemistry for the synthesis of functionalised amides and ~, 1" and 8-lactams. Organocobalt chemistry was born from the isolation and characterisation of the vitamin B12 coenzyme (2) in the 1950s and early 1960s. The introduction to this thesis covers the search for vitamin B12 and briefly describes its biological role. Next, the considerable development of the simple vitamin B12 analogues, i.e. organocobalt (II) salophens (10), is outlined. Finally, the exploitation of organocobalt (III) complexes in synthetic organic chemistry is detailed. The preparation of nitrogen heterocycles is initially addressed, with a study of the viability of carbamoylcobalt (III) salophen compounds, i.e. (68), as sources of carbamoyl radicals, i.e. (73), in Chapter 1 of the thesis. Thus, radical quenching, employing several heteroatom trapping agents, successfully afforded the amide derivatives (74) and (75). In addition, carbamoyl radicals were induced to undergo intermolecular oxidative additions to deactivated alkenes, under both thermal and photolytic conditions, to secure the cinnamamides (77) and (78). A unique approach to /3-, y- and o-lactams using cobalt-mediated radical chemistry is described in Chapter 2. Thus, the carbamoylcobalt (m) salophen (111) underwent sequential homolysis, 4-exo-trigonal radical cyclisation, and radical-cobalt (II) recombination, to create the unusual azetidin-2-one (114), which was subsequently transformed into the alcohol (125). Computer generated molecular modelling calculations supporting the novel radical cyclisation are presented. Next, analogous cyclisations are described with the homologous carbamoylcobalt (III) salophens (138) and (150). Subsequent in situ dehydrocobaltation secured the y-lactams (140) and (141), and the 8-lactams (151) and (152). Results concerning the introduction of oxygenation in tandem with cyclisation are also presented in Chapter 2. Chapter 3 of the thesis describes a novel synthetic approach to the broad-spectrum antibiotic (+)-thienamycin (56), harnessing a cobaltmediated 4-exo radical cyclisation as the key step. Model studies showed that the cyclisation would tolerate a range of substitution around the precursor, i.e. (165) and (179), and that the stereochemical outcome delivers the required 3,4-trans geometry for thienamycin, i.e. (187)~(182). Our initial synthetic target towards (56) was the acid (196), but the route was abandoned when the carbamoyl chloride (193) failed to yield the organocobalt (III) compound (194) on treatment with sodium cobalt (I) salophen (12). However, our second approach was successful and culminated in the preparation of the /J-lactam (200), which constituted a fonnal synthesis of (+)-thienamycin. Our synthetic route to (200) involved: (i) the preparation of the amine (197) via Wittig methodology, i.e. (203)~(205); (ii) conversion of (197) to the radical precursor (198); (iii) a 4-exo radical cyclisation to afford the 3,4-transazetidin- 2-one (199) and finally, (iv) a two step sequence to yield the /3- lactam (200).

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4

Kim, Byeongmoon 1957. "Asymmetric organic synthesis using organoboron compounds". Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14679.

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5

Sharma, Y. "Continuous flow synthesis of organic compounds". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2017. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4520.

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6

Haughey, Simon Anthony. "Chemoenzymatic synthesis of organosulfur compounds". Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318731.

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7

Kou, Xiaodi. "Synthesis, characterization and reactivity of organic bismuth compounds". Fort Worth, Tex. : Texas Christian University, 2007. http://etd.tcu.edu/etdfiles/available/etd-07312007-125631/unrestricted/kou.pdf.

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8

Wallner, Olov. "Palladium-Catalyzed Synthesis and Transformations of Organometallic Compounds". Doctoral thesis, Stockholm : Dept. of Organic Chemistry, Stockholm University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-804.

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9

Wang, Haofan. "Synthesis and reactions of organoiron compounds". Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/289994.

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The multistep synthesis of the redox active adenine analog [e]-ferrocenyl-4-aminopyrimidine is reported. The redox active system will be incorporated into oligonucleotides to study the electron transfer through the molecular pi-system of DNA in future studies. Attempts were made to synthesize a cyclopenta-4-aminopyrimidine derivative which possesses an endocyclic double bond in the cyclopentane ring. This intermediate can be subsequently coupled with cyclopentadienyl iron dicarbonyl (Fp) group and, after thermal decarbonylation, form the desired ferrocene ring. Many double bond precursors are prepared, including dibromide, acetate, alcohol, ketone and phenylseleno derivatives of cyclopentapyrimidine. However efforts to form an endocyclic double bond turned out to be unsuccessful. Exocyclic double bond derivatives of cyclopentapyrimidine have also been prepared. An improved chiral synthesis of [e]-ferrocenyl-4-aminopyrimidine is achieved, in which a Curtius rearrangement to form an O-benzylcarbamate was done using a formyl ferrocene carboxylic acid. The yield of the final cyclization step was also greatly improved. The synthesis of methyl-(2,5-dimethoxy-4-fluorophenyl)-acetate, a thymine isostere precursor, is reported. It will be used as a substitute for a thymine base in a peptide nucleic acid (PNA) synthesis in the future. Regioselective bromination of 2-fluoro-hydroquinone introduced a bromo group at the desired position. After protection of hydroxyl groups in this product, a carboxylic acid ethyl ester group was introduced. Finally, an Arndt-Eistert reaction was used to extend the carboxylic acid by one carbon to the corresponding phenyl acetic acid ethyl ester. A chemical model mimicking the biosynthesis of the cyanide ligand in the enzyme hydrogenase is developed. In this model a thiocarbamate is first formed and subsequently dehydrated by polyphosphate ethyl ester(PPE) to make a thiocyanate. Finally, the cyanide moiety is transferred to the metal center. The direct dehydration of a carboxamidoiron species to form a cyano ligand is also reported.

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10

Buckley, Anne Margaret. "Inorganic-organic layer compounds : synthesis and properties". Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253398.

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11

Hamilton, A. L. "Applications of lithium compounds in organic synthesis". Thesis, Swansea University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637209.

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The lithiation and subsequent condensation with an electrophile is a useful reaction in many 'total' syntheses. This study was undertaken to investigate the lithiation reactions of several organic molecules. In Chapters 2 and 3, the lithiation of a range of N-pivaloyl-o-toluidines was studied, with the resultant formation of indoles (Chapter 2) and reaction with carbon monoxide to form a carbonylated product (Chapter 3). The lithiation reaction was then applied to 2,5-dimethyl-1,4-phenylene-di-N-pivaloylamine as an attempt to effect quadruple lithiation. However, only double lithiation was observed. In Chapter 4, the attempted lithiation of trifluoroacetylanilines, was studied to see whether it is possible to effect lithiation on the aromatic ring to yield a dianion. Both alkyl and aryllithium reagents were observed to act as nucleophiles towards the substrates, resulting in displacement of the trifluoromethyl group. In Chapters 5, 6 and 7, lithiation of pyridones was investigated. Lithiation and electrophile trapping were found to readily occur for 3-methyl- (Chapter 6) and 6-methyl-2-pyridone (Chapter 5). However, the research on 4-methyl-2-pyridone (Chapter 6) showed that n-butyllithium caused either (i) lithiation at the 4-position in the ring or (ii) acted as a nucleophile, with the addition of a butyl group at the 6-position in the ring. The reaction of n-butyllithium and 3-cyano-6-methyl-2-pyridone was studied (Chapter 7). n-Butyllithium was found to act as a nucleophile towards 3-cyano-6-methyl-2-pyridone, resulting in the addition of a butyl group.

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12

Adiraju, Kiran A. V. "Synthesis and characterization of organic-inorganic colorants". To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.

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13

Mantell, Simon J. "Synthesis of highly functionalised homochiral compounds". Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334895.

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14

King, Alistair William Thomas. "Chemoenzymatic synthesis of chiral organosulfur compounds". Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396118.

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15

Ducept, Pascal. "Synthesis of heterocycles using silyldiazocarbonyl compounds". Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271307.

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16

Lee, Danny Ka Ming. "Unsaturated sulfinates and sulfoxides in organic synthesis". HKBU Institutional Repository, 1995. http://repository.hkbu.edu.hk/etd_ra/47.

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17

Ikegami, Toru. "Hypervalent Organobismuth Compounds : Synthesis, Reaction, and Applications to Organic Synthesis". 京都大学 (Kyoto University), 1997. http://hdl.handle.net/2433/86484.

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18

BERTON, GIACOMO. "SYNTHESIS OF TRIPHENYLENES FOR SUPRAMOLECULAR APPLICATIONS". Doctoral thesis, Università degli Studi di Trieste, 2020. http://hdl.handle.net/11368/2969361.

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In this Doctoral Thesis, through several examples of new chemical modifications characterized by high yields and selectivities and new supramolecular structures, held together by a wide range of intermolecular forces forming several new host systems, we reached our target to revamp triphenylene and derivatives as a new molecular scaffold in supramolecular chemistry. More specifically, the introduction in our triphenylenic scaffold of alkyl thiol chains allowed the formation of sulphide and disulphide covalent cages, while by insertion of pyridine moieties through Mannich reaction it was possible to obtain transition metal coordination cages upon addition of metal corners. The creation of a tris-acid from the original scaffold allowed the investigation of self-aggregation capsules through hydrogen bonds between carboxylic acids, and the functionalization with charged polytails attached to the central triphenylenic core, alternated with apolar substituents, allowed solubilization in water with the formation of very small micelles. Moreover, the interaction between positively charged and negatively charged triphenylenes permitted the creation of peculiar ionic hetero-dimeric capsules. We are sure that this will spur future investigation on the capsules and cages presented in this work, enriching the scientific community involved in this interdisciplinary field of research.

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19

Frankowski, Kevin J. "Carbenes and carbenoids as powerful tools in organic synthesis". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.18 Mb., 94 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3205422.

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20

Guertin, Kevin Richard. "The synthesis of highly oxygenated decalin compounds". Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39396.

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The Lewis acid catalysed tandem Michael-Claisen (4C + 2C) annelation reaction of 1-trimethylsiloxy-1-methoxy-3-phenylthio-1,3-butadiene and 4,4-dimethyl-2-cyclohexen-1-one has been reexamined. The intermediate E and Z Michael adducts were cyclized under basic conditions to give the $ beta$-diketone 3-phenylthio-5,6,4a,8a-tetrahydro-5,5-dimethyl-(4H,7H)-naphthalen-1,8-dione. Angular methylation of this $ beta$-diketone under basic conditions was examined in detail, providing the cis angularly methylated product stereoselectively.
The cis ring junction stereochemistry of the $ beta$-diketone derivative mentioned above has been used advantageously to establish the C$ sb8$ (naphthalene numbering) $ alpha$-hydroxyl stereochemistry required for the forskolin structure. A subsequent enolate oxidation/nucleophilic addition sequence was then used to stereoselectively install the C$ sb1$ and C$ sb2$ (naphthalene numbering) cis $ alpha, alpha$-diol functionality also present in the forskolin structure. Subsequent functional group manipulations then provided 1,2,5,6,7,8,8a-heptahydro-$1 alpha,2 alpha$,4-${ rm trihydroxy}$-8$ alpha$-(tert-butyldimethylsiloxy)-$1 beta(1 sp prime$-${ rm hexynyl}$)-2,5,5,8a$ beta$-tetramethyl-naphthalen-3-one, a highly oxygenated $ alpha$-diketone intermediate for the synthesis of forskolin.
A number of the decalin compounds leading to the $ alpha$-diketone intermediate mentioned above, were tested for antifeedant activity against the spruce budworm (Choristoneura fumiferana). Eleven of these compounds were found to be active and structure-activity relationships were examined.

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21

Stessman, Nhu Y. Tran. "Synthesis, structures and studies of organoiron compounds". Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/283985.

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An A value of 3.7 kcal/mole was determined for the (η⁵-cyclopentadienyl) iron (II) dicarbonyl group by variable temperature ¹H NMR spectroscopic studies on cis-4-phenyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane. This is the first determination of the A value of a group with a transition metal directly attached to a cyclohexane ring. The energy of activation (-ΔG‡) for ring inversion of cis-4-phenyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane was calculated to be 9.4 kcal/mol. The stereospecific synthesis of cis- and trans-4-phenyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane, cis- and trans-4-tert-butyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane and the X-ray crystal structure of cis-4-tert-butyl-1-(η⁵-cyclopentadienyl) iron (II) dicarbonyl cyclohexane are reported. The multistep stereospecific synthesis of the redox active adenine analog (S)-ferrocenyl-4-aminopyrimidine is reported. This redox active system will be incorporated into oligonucleotides to study the electron transfer through the molecular π-stack system of DNA in future studies. This synthesis used a chiral metalation to synthesize α-aminoferrocenenitrile. t-Butylcarbamate as the metalation-directing group gave a low yield of the 1,2-disubstituted ferrocene. N,N-diisopropylcarboxamide as the metalation-directing group using a chiral base gave moderate yields of 1,2-disubstituted ferrocene derivatives. However, standard hydrolytic methods failed to hydrolyze the diisopropylamide grouping in these 1,2-disubstituted ferrocene derivatives. A new method was developed to convert the amide functionality of N,N-diisopropylferrocenecarboxamide to ester functionality using Me₃O⁺BF₄⁻, NaOMe and an acidic workup. Unfortunately, when this condition was applied to iodo-N,N-diisopropylferrocenecarboxamide and amino-N,N-diisopropylferrocenecarboxamide, only starting materials and N',N'-dimethylamino-N,N-diisopropylferrocenecarboxamide were obtained, respectively. A chiral acetal as the metalation-directing group was used to give stereoselectively (S)-α-carbomethoxyferrocenecarboxaldehyde after the hydrolysis of the acetal group. The aldehyde was then converted to the nitrile, and the ester group was converted to an amino group to give (S)-α-aminoferrocenenitrile. In a two step sequence, (S)-α-aminoferrocenenitrile was reacted with HC(OMe)₃ and gaseous ammonia to give (S)-α-ferrocenyl-4-aminopyrimidine.

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22

Sacripante, Guerino. "Radical reactions in organic synthesis". Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75340.

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The 4-substituted glutarimide required for the synthesis of sesbanimide (53) was obtained by free radical addition of iodoacetamide onto the $ alpha, beta$-unsaturated ester (81) mediated by tributyltin; the lactol ring C was prepared by the analogous free radical cyclization of the $ alpha$-bromo-dipropargyl ketal 73.
The syntheses of tricyclic carbapenems involved appropriately substituted monocyclic azetidinone precursors. Free radical 5- exo cyclizations led to the relatively unstable benzo carbapenems 116, 119 and 120. The 6- exo mode, however, afforded stable benzo carbacephems 125, 127, 132 and 133.
$ alpha$-Bromo- and $ alpha{,} alpha$-dibromoazetidinones were converted stereoselectively to the $ alpha$-alkylazetidinones 149 and 153, or to $ beta$-alkylazetidinones 151, 154 and 159 by a free radical addition onto olefins 148 or allyltributyltin.

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23

Ye, Xiangyang. "I. Enantioselective total synthesis of ( - )-triptolide : II. synthesis of triptolide analogs /". Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20896918.

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24

Rowley, Michael. "Some uses of tin compounds in organic synthesis". Thesis, University of Cambridge, 1986. https://www.repository.cam.ac.uk/handle/1810/265341.

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The work described in the dissertation is concerned mainly with organo-tin chemistry. In the first part, I describe the investigation of the stereochemistry of intramolecular electrophilic attack on a tin-carbon bond. The react ion of a number of cS - and � -s tanny 1 a lcoho 1 s and 0-stannyl acid chlorides was investigated, but stereochemical information was obtained only with the reaction of a 0-stannyl aldehyde to give a cyclopentanol, which proceeded largely with retention of configuration at the tin-bearing carbon, unlike the reaction of cS -stannyl alcohols, which give cyclopropanes with inversion. The second piece of work is a regio- and stereo-specific synthesis of allyl stannanes. s-stannyl ester enolates were treated with aldehydes to give alcol products with fairly good stereoselectivity: (~) and (~) enolates gave major products with different aldol relative stereochemistry. These aldols could be converted to s - hydroxy acids, then treatment with d imethy 1 formamide dimethyl acetal gave allyl stannanes stereospecifically, where steric and reactivity effects allowed. Thirdly, an investigation of the reaction of a tin cuprate with allenes is described. The cuprate reacts with 1,1-dimethyl allene followed by aqueous work up to give an allyl stannane, or the intermediate copper species can be quenched with a number of different ele,ctrophiles to give further substituted allyl stannanes. Similarly, allene itself reacts to give either vinyl or allyl stannanes, depending on the conditions used. Unfortunately, the factors governing the regiochemistry of the reaction with allene are not yet fully understood, and mixtu r es of products often result. Finally, I describe efforts to perform a kinetic resolution of a racemic Grignard reagent in which the chiral centre is the meta 1-bear ing carbon. It was hoped that react ion of the Gr ignard with half an equivalent of an optically active carbonyl compound would leave the remaining Gr ignard partially reso 1 ved. However, this did not prove to be successful.

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25

Roper, Kimberley Ann. "New flow chemistry methods for organic synthesis". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607846.

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26

Saito, Yu. "Synthesis of bioactive compounds: Synthetic study of D-Lac-terminated peptidoglycan fragment structures". Thesis, KTH, Kemiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-300085.

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Abstract (sommario):

Peptidoglycan (PGN) är en bakteriecellväggskomponent och känd för att känna igen olika receptorer eller enzymer för att leda aktiveringsimmunsystemet. Den allmänna strukturen för PGN består av sockerkedjor inklusive N-acetylglutamin (GlcNAc), N-acetylmuraminsyra (MurNAc) och tvärbundna peptidkedjor. PGN-fragment med D-Lac-ändpeptider har hittats från vankomycinresistenta enterokocker men ett kemiskt syntetiserat PGN-fragment med en D-Lac-ändpeptid har inte undersökts i detalj. Således fokuserade vi på syntesen av PGN-fragmentstrukturer som inkluderar en D-Ala-D-Lac-rest vid den terminala delen av peptidkedjan. För att syntetisera dessa fragmentstrukturer planerade vi att kombinera fastfassyntes (för Lac-peptiddelen) och lösningsfassyntes (för glykanberedning och kondensation). Detta tillvägagångssätt är fördelaktigt för framställning av peptidoglykanfragment med en komplex grenad peptiddel. Först beredde vi sockerdelen MurNAc-derivatet i lösningsfassyntes från ett glukosderivat. Medan den Lac-innehållande peptiden framställdes med fastfas-peptidsyntes med användning av 2-klortritylkloridharts. Med denna förening gav kondensationen av dessa två föreningar det önskade D-Lac-avslutade peptidoglykanfragmentet.
Peptidoglycan (PGN) is a bacterial cell wall component and known to be recognized by various receptors or enzymes to lead the activation immune system. The general structure of PGN consists of sugar chains including N-acetylglutamine (GlcNAc), N-acetylmuramic acid (MurNAc) and cross-linked peptide chains. PGN fragments having D-Lac terminus peptides have been found from vancomycin-resistant enterococcus, but a chemically synthesized PGN fragment having a D-Lac terminus peptide has not been examined in detail. Thus, we focused on the synthesis of PGN fragment structures that include a D-Ala-D-Lac residue at the terminal part of the peptide chain. In order to synthesize these fragment structures, we planned to combine solid-phase synthesis (for the peptide- Lac part) and solution-phase synthesis (for glycan preparation and the condensation). This approach is advantageous for the preparation of peptidoglycan fragments having complex branched peptide moiety. First, we prepared the sugar moiety MurNAc derivative in solution-phase synthesis from a glucose derivative. While, the Lac-containing peptide was prepared with solid-phase peptide synthesis using 2-chlorotrityl chloride resin. Having this compound, the condensation of these two compounds gave the desired D-Lac-terminated peptidoglycan fragment.

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27

Rujiwatra, Apinpus. "Synthesis and characterisation of novel framework compounds". Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365355.

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28

McMurray, Brian Thomas. "Chemical and enzymatic synthesis of organosulphur compounds". Thesis, Queen's University Belfast, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359111.

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29

Hadjipavlidis, V. "Synthesis and reactions of some spiroheterocylic compounds". Thesis, Nottingham Trent University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.354396.

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30

Tran, Chuong Hao. "Synthesis of pseudo-sugars and related compounds". Thesis, University of Warwick, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308507.

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31

Edmondson, S. J. "Synthesis, properties and applications of phthalocyanine compounds". Thesis, University of Reading, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378676.

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32

Shirtcliff, Laura Donnell. "'Coarctate' cyclizations : applications to heterocycle synthesis /". view abstract or download file of text, 2006. http://proquest.umi.com/pqdweb?did=1188876631&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.

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Abstract (sommario):

Thesis (Ph. D.)--University of Oregon, 2006.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 336-357). Also available for download via the World Wide Web; free to University of Oregon users.

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33

Hurley, Jeffrey S. "Synthesis of organic compounds exhibiting enhanced nonlinear optical effects". Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/27133.

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34

Dutta, Somnath. "Alkylzirconium alkoxides in organic synthesis reactions with sigma- and pi-bonded organic substrates /". Online access via UMI:, 2005.

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35

Fryling, James Allen 1959. "AN ENANTIOSELECTIVE SYNTHESIS OF BETA-EUDESMOL (DIASTEREOSELECTIVE, CYCLOPROPANATION)". Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/291680.

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36

Law, Ga-lai, e 羅嘉麗. "Synthesis and photophysical studies of organic lanthanide complexes". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38308216.

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37

Tatebe, Caleb J. "Synthesis of Sugar-Derived Esters and Carbamate Compounds". Youngstown State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1409833972.

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38

Law, Ga-lai. "Synthesis and photophysical studies of organic lanthanide complexes". Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38308216.

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39

Rhodes, J. B. "Synthesis of 1,6,6aLambdasup(4)-triheterapentalenes and related compounds". Thesis, University of St Andrews, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373044.

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40

Gardner, Helen. "New methods for the synthesis of amino compounds". Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357640.

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41

Barrell, Juliet Kay. "The asymmetric synthesis of #alpha#-heterosubstituted carbonyl compounds". Thesis, University of Sheffield, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312778.

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42

Walterson, George H. "Direct synthesis and stabilities of unsymmetrical triorganotin compounds". Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293488.

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Abstract (sommario):

The syntheses of a variety of triorganotin bromides of general formula RBu₂SnBr were attempted by reaction of dibutyltin dibromide, an alkyl bromide (RBr), tin and tetrabutylammonium bromide. With the exception of tributyltin bromide which was prepared as a fairly pure compound where R was a butyl group, all other products were mixtures of organotin bromides. In order to identify the compounds of the type RBu₂SnBr in these products, tetraorganotins of general formula, RBu₂PeSn, were prepared as GLC standards by a sequence of selective dephenylation and alkylation starting from dibutyldiphenyltin. The solubility of the organotin bromide products in aqueous sodium chloride solution was investigated by atomic absorption spectroscopy. In general, solubility was enhanced by functional groups such as ethers in the sidechain R due to hydrogen bonding, while it was lowered by the presence of longer chain organic groups. The stability of organotin bromide mixtures containing propyl, isobutyl and 3-butenyl groups was assessed in sterile, artificial seawater in darkness for periods of approximately one year. No decomposition was detected under these conditions. Decomposition was effected by placing organotin bromides in aqueous sodium hydroxide solution with UV irradiation by a medium pressure mercury vapour lamp. It was found that organic groups such as 2-butoxyethyl showed significant decomposition while those with functional groups situated well away from the tin centre or no functional groups showed no appreciable tin-carbon bond cleavage. Ozone reacted with the organotin bromides at tin-carbon bonds, in general giving tetraorganodistannoxane products, and also at functional groups, for example a sulphide was converted to the corresponding sulphoxide and sulphone. The syntheses of a range of symmetrical triorganotin bromides were also attempted with varying results.

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43

goyal, Navneet. "Synthesis and biological evaluation of aeruginosin based compounds and self-assembly of glucosamine based compounds". ScholarWorks@UNO, 2011. http://scholarworks.uno.edu/td/1395.

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Abstract (sommario):

Aeruginosins are a family of marine natural products containing mostly non-proteogenic amino acids. These compounds contain a common 2-carboxy-6-hydroxy-octaindole (Choi) rigid bicyclic structure. Many aeruginosins are inhibitors for enzymes involved in the blood coagulation cascade, such as thrombin and Factor VIIa. In order to understand the structure activity relationship (SAR) of the aeruginosins and to discover novel anticoagulants with potentially improved inhibitory and pharmacokinetic properties, in the first part of my thesis I have discussed, synthesis of a series of novel analogs of aeruginosin 298-A, in which the Choi will be replaced with L-proline and oxygenated Choi analogs, and the Argol is replaced with various other functionalities. The preparation of oxygenated Choi analogs starting from glucose using a new method has been discussed. In the second part of my dissertation, I have discussed the design, synthesis and self–assembly of glucosamine based hydro and organogelators. Carbohydrate-based low molecular weight gelators are an interesting class of molecules with many potential applications. A series of amides and ureas were prepared from the protected D-glucosamine from the corresponding acid chloride and isocyanates. The self-assembling properties of these compounds were studied in several solvents, including water and aqueous solutions. Most of these compounds were found to be efficient low molecular weight hydrogelators (LMHGs) for aqueous solutions. The preparation and characterization of these compounds will be elaborated.

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44

Mahanjana, Lungelwa. "Reactions towards the synthesis of the uncommon P57 cymarose moiety". Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/6711.

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Abstract (sommario):

The work described in this study aims to investigate methods that will improve a lengthy synthetic pathway in the synthesis of the P57 cymarose moiety, and to examine the conformational structure of certain glycosides in order to shed light on the problematic stereochemical issues surrounding the formation of the cymarose glycosyl donor. The cymarose moiety forms part of the trisaccharide derivative present in P57, an appetite suppressant molecule. Modification of reaction steps in the conversion of the stereochemistry at C-3 of a previously reported synthesis of the P57 cymarose moiety was carried out. The first step was the selective oxidation of D-glucal using Pd/C in the presence of acetonitrile. These reaction conditions are more appropriate for the oxidation step to avoid decomposition of the formed molecules. Successive protection of the free OH groups was followed by NaBH4 reduction under stereo-controlled conditions, influenced by CeCl3•7H2O. However, the reduced product could not be isolated from the starting material and this led to ambiguous results when attempting to confirm whether the conversion of the stereochemistry at C-3 had occurred or not. The effect of reaction conditions, such as change in reaction temperature, during the preparation of the cymarose glycosyl donor was studied in order to find suitable reaction conditions to produce α,β-allo derivatives with high stereoselectivity. Compared to the reported synthetic method, this set-up gave improved yields with, unfortunately, similar or slightly lower selectivity to the formation of α-altro:α,β-allo derivative. Examination of the conformational structure of the allal derivative, in order to understand the mechanism at work during the placement of the directing group at C-2, was carried out using molecular modelling. The mechanistic implications of this very short study are discussed and it provides some insights into the likely pathway of the iodination reaction and its selectivity in particular, to the D-allose system.

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45

Crump, Roger Adrian Neil Callow. "Enantio- and diastereocontrol with silicon compounds in organic synthesis". Thesis, University of Cambridge, 1993. https://www.repository.cam.ac.uk/handle/1810/272577.

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46

Zhou, Yi. "Organic synthesis and fungicidal activity of oxylipin-based compounds". Thesis, Aston University, 2011. http://publications.aston.ac.uk/13365/.

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Abstract (sommario):

Previous research has shown that the naturally occurring reactive electrophilic species (RES), 12-oxophytodienoic acid (OPDA), not only serves as a precursor for jasmonic acid but is also a potent antifungal compound. However, both the low amount present in plants and the multistep synthesis required to produce this compound on a scale viable for agrochemical use currently limits its practical value. The aim of this research was to generate a range of molecular mimics of OPDA with a minimum number of synthetic steps and screen for antifungal activity. Synthetic 4-octyl-cyclopentenone containing the cyclopentenone ring and an eight carbon alkyl chain was found to show the highest in vitro antifungal activity against C. herbarum and B. cinerea with minimum inhibition concentration (MIC) of 100-200µM. This indicates that structurally simplified 4-octyl-cyclopentenone can be successfully synthesised to mimic the antifungal activity of OPDA against specific fungal strains. Application of 4-octyl-cyclopentenone could act as surfactant by disrupting and disorganising the lipid membrane non-specifically, resulting in the leakage of potassium ions, which was the proposed mode of action of this compound. However, the sensitivity of fungi to this compound is not correlated to the lipid composition of fungal spores. (E)-2-alkenals were also studied for their antimicrobial activity and (E)-2-undecenal was found to have the highest antimicrobial activity against a range of pathogens. The hydrophilic moiety (the a,ß-unsaturated carbonyl group), common to both (E)-2-undecenal and 4-octyl-cyclentenone is essential to their bioactivity, and the hydrophobic moiety plays an important role in their antimicrobial activities. 4-Octyl-cyclopentenone showed no visible toxicity to the test plant, Arabidopsis thaliana, suggesting that its high antifungal activity against Botrytis and Cladosporium could be exploited for commercialisation as a new generation of agrochemical.

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47

Kewley, Adam. "The synthesis and separation properties of organic cage compounds". Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2010659/.

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Abstract (sommario):

Microporous materials play an important role in a variety of industrial and domestic applications. While a diverse range of microporous materials have been identified, this thesis focuses on porous organic cages (POCs) because they have received much attention as synthetically tunable, solution processable, microporous materials. After introducing the latest developments in POC synthesis and the general application of microporous materials as selective sorbents, this thesis presents three developments in organic cage chemistry: a high-throughput workflow for the discovery of POCs, which yielded a novel organic cage compound; the measurement of selective adsorption by POCs, wherein the first instance of chiral selectivity by a POC was recorded; and the first instance of applying POCs as stationary phases for gas chromatography, which produced columns that separate racemic mixtures, alkylaromatic isomers, and alkane isomers. Chapter 2, discovering novel organic cages, presents attempts to use high-throughput and in-silico techniques to accelerate the discovery of novel organic cages. These methods were utilised to isolate a novel organic cage, CCX-S, which is characterised and discussed. Chapter 3, organic cages as selective sorbents, presents the development of approaches for measuring selective adsorption. These methods were used to identify the first reported instance of enantioselective adsorption by an organic cage. Further measurements to explain this separation behavior are also presented. Chapter 4, chromatographic separations with organic cages, presents one method of practically leveraging the presented separation behavior. In Chapter 4, the coating of capillary columns with CC3 is presented. These columns were used to successfully perform gas chromatographic separations, the first recorded instance of using a POC to do so. The columns were further improved by modifying the coating method and using prefabricated CC3 nanoparticles. This modification enabled difficult separations to be performed using the column; for example, the separation of hexane’s five isomers.

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48

Mitchell, Michael Anthony. "Synthesis and evaluation of new nonlinear optical organic compounds". Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185377.

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Abstract (sommario):

Nonlinear optical (NLO) materials are of current interest because of their potential applications in the development of optical computers, switches, and information storage devices, as well as laser attenuation. Organic molecules with a donor group and an acceptor group connected through a pi system exhibit a large second order NLO response, the NLO characteristic of the most interest. Previous studies have suggested that by having the NLO molecular units connected in series there is a synergistic enhancement of the NLO effect. In an effort to study this enhancement various p-aminophenyl sulfone monomers, dimers, and trimers were synthesized and evaluated. The results from this study did not confirm such enhancement, and indicate that much more work needs to be done. Also, another class of monomer which was expected to have a high NLO efficiency was synthesized. These monomers were polymerized via condensation polymerization to give the polyesters, which contained a stilbene moiety. These polymers were found to be tractable and possess a high glass transition temperature, which is very desirable. Finally, a method based on simple spectrophotometric measurements, and ground state dipole moment measurements, was evaluated and refined. This method, while not as accurate as standard techniques, is low cost, and simpler to conduct.

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49

Perez, Fuertes Yolanda. "New strategies using BINOL-boron compounds for organic synthesis". Thesis, University of Bath, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.414606.

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50

Long, Sha <1983&gt. "Design, Synthesis and Characterization of N-Containing Organic Compounds". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5624/1/LONG_SHA_TESI.pdf.

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Abstract (sommario):

The needed of new intermediates/products for screening in the fields of drug discovery and material science is the driving force behind the development of new methodologies and technologies. Organic scaffolds are privileged targets for this scouting. Among them a priority place must be attributed to those including nitrogen functionalities in their scaffolds. It comes out that new methodologies, allowing the introduction of the nitrogen atom for the synthesis of an established target or for the curiosity driven researches, will always be welcome. The target of this PhD Thesis’ work is framed within this goal. Accordingly, Chapter 1 reports the preparation of new N-Heteroarylmethyl 3-carboxy-5-hydroxy piperidine scaffold, as potential and selective α-glucosidase inhibitors. The proposed reversible uncompetitive mechanism of inhibition makes them attractive as interesting candidate for drug development. Chapter 2 is more environmentally method-driven research. Eco-friendly studies on the synthesis of enantiomerically pure 1,4-dihydropyridines using “solid” ammonia (magnesium nitride) is reported via classical Hantzch method. Chapter 3 and Chapter 4 may be targeted as the core of the Thesis’s research work. Chapter 3 reports the studies addressed to the synthesis of N-containing heterocycles by using N-trialkylsilylimine/hetero-Diels–Alder (HAD) approach. New eco-friendly methodology as MAOS (Microwave Assisted Organic Synthesis) has been used as witness of our interest to a sustainable chemistry. Theoretical calculations were adopted to fully clarify the reaction mechanism. Chapter 4 is dedicated to picture the most recent studies performed on the application of N-Metallo-ketene imines (metallo= Si, Sn, Al), relatively new intermediates which are becoming very popular, in the preparation of highly functionalized N-containing derivatives, accordingly to the Thesis’ target. Derivatives obtained are designed in such a way that they could be of interest in the field of drug and new material chemistry.

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