Academic literature on the topic 'C-Hetero Bond'

This review highlights the recent advances in photochemical (hetero)aryl C(sp²)–C(sp³) bond construction via C–H bond coupling such as (hetero)arylation of C(sp³)–H bonds and alkylation of (hetero)aryl C(sp²)–H bonds.

Structures of the α-pyrone (pyran-2-one) cycloadducts 4–8 show deviations of some bond distances from their normal values, consistent with manifestation of the early stages of the retro hetero-Diels–Alder decarboxylation reaction in the ground state structures. Thus the bridgehead C–O(CO) and C–CO(O) bonds are lengthened and the bridging C–O bond is shortened. The degree of lengthening of the C–O(CO) and C–CO(O) bonds is similar, whereas in the calculated transition state structure there is significant asymmetry in the extent of C–CO(O) and C–O(CO) bond breaking.

The functionalization of typically unreactive C(sp3)–H bonds holds great promise for reducing the reliance on existing functional groups while improving atom-economy and energy efficiency. As a result, this topic is a matter of genuine concern for scientists in order to achieve greener chemical processes. The site-specific modification of α-amino acid and peptides based upon C(sp3)–H functionalization still represents a great challenge of utmost synthetic importance. This short review summarizes the most recent advances in ‘Cross-Dehydrogenative Couplings’ of α-amino carbonyl compounds and peptide derivatives with a variety of nucleophilic coupling partners.1 Introduction2 C–C Bond-Forming Oxidative Couplings2.1 Reaction with Alkynes2.2 Reaction with Alkenes2.3 Reaction with (Hetero)arenes2.4 Reaction with Alkyl Reagents3 C–Heteroatom Bond-Forming Oxidative Couplings3.1 C–P Bond Formation3.2 C–N Bond Formation3.3 C–O and C–S Bond Formation4 Conclusions

A new and facile KI/K2S2O8-mediated α-C–H sulfenylation of carbonyl compounds with (hetero)aryl thiols was developed for the formation of C–S bond at room temperature. This method provided a simple process for the synthesis of β-keto thioethers in moderate to excellent yields. A variety of carbonyl compounds and (hetero)aryl thiols were tolerated in this reaction.

A radical relay strategy has been developed to enable selective δ C–H arylation. The approach employs a chiral copper catalyst, which serves the dual roles of generating an N-centered radical to promote intramolecular H-atom transfer, and then intercepting a distal C-centered radical for C–C bond formation with (hetero)aryl boronic acids.

An iron-catalyzed cross-coupling between di(hetero)arylmanganese reagents and primary and secondary alkyl halides is reported. No rearrangement of secondary alkyl halides to unbranched products was observed in these C–C bond-forming reactions.

A short and robust approach for the synthesis of 2-(hetero)aryl substituted thieno[2,3-b]indoles from easily available 1-alkylisatins and acetylated (hetero)arenes has been advanced. The two-step procedure includes the “aldol-crotonic” type of condensation of the starting materials, followed by treatment of the intermediate 3-(2-oxo-2-(hetero)arylethylidene)indolin-2-ones with Lawesson’s reagent. The latter process involves two sequential reactions, namely reduction of the C=C ethylidene double bond of the intermediate indolin-2-ones followed by the Paal–Knorr cyclization, thus affording tricyclic thieno[2,3-b]indoles.

A simple and efficient electrochemical method for the synthesis of asymmetrical bi(het)aryls through direct functionalization of the C(sp²)–H bond in azaaromatics with fragments of (hetero)aromatic nucleophiles has been developed.

Afin d'expliquer le contexte de mon travail de recherche, j'ai résumé dans le premier chapitre des informations mécanistiques générales sur l'arylation des liaisons C-H catalysée par le palladium et j'ai détaillé certains travaux sur l'arylation directe en relation avec mes travaux. Mes objectifs étaient d'étudier la réactivité de nouvelles unités synthétiques permettant l'accès direct à des composés bi-(hétéro)aryls ou à des dérivés du styrène. Ensuite, dans les chapitres 2 à 6, j'ai résumé mes travaux de recherche. J'ai étudié l’arylation directes en C2 du Methoxsalen par des chlorures de benzènesulfonyle, ainsi que la diarylation en C2,C3 en utilisant des bromures d'aryle catalysée par le palladium. Ces résultats sont résumés dans le chapitre 2. Ensuite, j'ai montré que la réaction d'arylation directe catalysée par le palladium permet d'accéder facilement à des dérivés de la Ticlopidine arylés en position C5 du cycle thiényle en une seule étape. Ces résultats sont décrits dans le chapitre 3. Dans le chapitre 4, nous avons étudié la réactivité du Diflufénican qui contient un cycle 1,3- difluorobenzène et une unité pyridine en utilisant la catalyse au ruthénium et au palladium. Dans des conditions appropriées, deux liaisons C-H différentes du Diflufénican peuvent être arylées. Dans le chapitre 5, j'ai utilisé différentes sources d’aryle pour fonctionnaliser les positions C10 et C11 des dibenzo[b,f]azépines. Grâce à ces réactions, une grande diversité de groupes fonctionnels a été introduite sur les dérivés de dibenzo[b,f]azépines. Enfin, dans le chapitre 6, j’ai décrit la première méthode permettant de préparer des dérivés de la Cyproheptadine C10-arylés
In order to explain the background of my research work, in the first chapter, I summarized general mechanistic information on palladium-catalyzed C-H bond arylation and detailed some literature on direct arylation related to my research work. My objectives were to study the reactivity of new synthetic units allowing the straightforward access to bi-(hetero)aryls compounds or styrene derivatives using aryl halides or benzenesulfonyl chloride derivatives as the aryl-sources. Then, in the chapters 2-6, I summarized my research work. I studied the regiocontrolled palladium-catalyzed direct C2-arylations of Methoxsalen using benzenesulfonyl chlorides and C2,C3-diarylations using aryl bromides as the aryl sources. These results are summarized in the chapter 2. Then, I found that Pd-catalyzed direct arylation reaction allows the easy access to Ticlopidine derivatives arylated at the C5-position of the thienyl ring in one step. These results are reported in the chapter 3. In the chapter 4, we studied the reactivity of Diflufenican which contains a 1,3-difluorobenzene ring and a pyridine unit using Ru and Pd catalysis. Under appropriate conditions, two different C-H bonds of Diflufenican could be arylated. In the chapter 5, I employed different aryl sources to functionalize the C10- and C11-positions of dibenzo[b,f]azepines, and obtained asymmetric products. Through these reactions, a wide diversity of functional group were introduced on the dibenzo[b,f]azepine derivatives. Finally, in the Chapter 6, I report the first method allowing to prepare C10-arylated Cyproheptadine derivatives

Au cours de cette thèse, nous nous sommes intéressés à l'activation de liaisons sp² et sp³ C-H catalysée par le palladium pour la préparation d'(hétéro)aryl-aryles et de biaryles. Cette méthode est considérée comme attractive pour l'environnement par rapport aux méthodes classiques, tels que Suzuki, Heck, ou Negishi. Tout d'abord, nous avons décrit que la C2-arylation directe de benzothiophènes peut être effectuée par un catalyseur du palladium en l'absence de ligand phosphine avec une grande sélectivité. Nous avons également démontré qu'il est possible d'activer les positions C2 et C5 de pyrroles pour accéder en une seule étape a des 2,5-diarylpyrroles. Des 2,5-diarylpyrroles non-symétriques ont été formés par arylation séquentielle en C2 suivie par une arylation en C5. Nous avons également étudié la réactivité de polychlorobenzenes pour l'activation de liaisons C-H catalysé au palladium. Nous avons finalement étudié l'activation sp² et sp³ sélective catalysé au palladium de liaisons C-H du guaiazulene. La sélectivité de la réaction dépend du solvant et de la base : C2-arylation (KOAc en éthylbenzène), C3-arylation (KOAc dans le DMAc) et C4-Me arylation (CsOAc/K₂CO₃ dans le DMAc). Grâce à cette méthode, une liaison sp³ C-H peu réactive a été activée
During this thesis, we were interested in the sp² and sp³ C-H bond activation catalyzed by palladium catalysts for the preparation of (hetero)aryl-aryls and biaryls. This method is considered as cost effective and environmentally attractive compared to the classical couplings such as Suzuki, Heck, or Negishi. First we described the palladium-catalyzed direct C2-arylation of benzothiophene in the absence of phosphine ligand with high selectivity. We also demonstrated that it is possible to active both C2 and C5 C-H bonds for access to 2,5-diarylated compounds in one step, and also to non-symmetrically substituted 2,5-diarylpyrroles via sequential C2 arylation followed by C5 arylation. We also studied the reactivity of polychlorobenzenes via palladium-catalyzed C-H activation. We finally examined the palladium-catalysed selective sp² and sp³ C-H bond activation of guaiazulene. The selectivity depends on the solvent and base: sp² C2-arylation (KOAc in ethylbenzene), sp² C3-arylation (KOAc in DMAc) and sp³ C4-Me arylation (CsOAc/K₂CO₃ in DMAc). Through this method, a challenging sp³ C-H bond was activated

The thesis entitled “Copper-Catalyzed Novel Oxidative Transformations: Construction of Carbon-Hetero Bonds” is divided into two main sections. Section A deals with the utility of azide as a nitrogen source for C-N bond formation, which is further divided into 4 chapters, and section B presents decarboxylative radical coupling reaction for C-heteroatom bond formation which is further divided in to two chapters. Section A Chapter 1 describes an approach for the direct synthesis of nitrile from the corresponding alcohols using azide as a nitrogen source. Nitrile functionality is a versatile and ubiquitous which occurs in a variety of natural products. Nitrile functionality can be easily transformed into a variety of functional groups and products such as aldehydes, ketones, acids, amines, amides and nitrogen-containing heterocycles, such as tetrazoles and oxazoles. In this chapter a successful attempt for developing a novel methodology to oxidize benzylic and cinnamyl alcohols to their corresponding nitriles in excellent yields has been described. This strategy uses DDQ as an oxidant and TMSN3 as a source of nitrogen in the presence of a catalytic amount of Cu(ClO4)2·6H2O. A few representative examples are highlighted in Scheme 1.1 Scheme 1. Oxidative conversion of alcohols to nitriles Second chapter represents a protocol for the synthesis of 1,5-disubstituted tetrazoles from the corresponding secondary alcohols. Among heterocyles, tetrazole and its derivatives are important class of nitrogen containing molecules. Due to their well-known biological activities as well as vast applications in pharmaceuticals and material science, they are potential targets for synthetic organic chemists. Therefore, a simple and user-friendly method for the synthesis of tetrazole is desirable. In this chapter, a mild and convenient method to synthesize 1,5-disubstituted tetrazoles using easily accessible secondary alcohols by employing TMSN3 as a nitrogen source is developed. This reaction is performed in the presence of a catalytic amount of Cu(ClO4)2·6H2O using DDQ as an oxidant under ambient conditions (Scheme 2).2 Scheme 2. Oxidative conversion of secondary alcohols to tetrazoles Third chapter presents a method for synthesizing amides from their corresponding secondary alcohols. Amide functionality is a crucial backbone in peptide chemistry, it also serve as an important precursor or intermediate for variety of organic transformations. In this contention, a mild and convenient method to synthesize amides using easily accessible secondary alcohols by employing TMSN3 as a nitrogen source is developed. This reaction is performed in the presence of a catalytic amount of Cu(ClO4)2·6H2O using DDQ as an oxidant under ambient conditions (Scheme 3).3 Scheme 3. Oxidative conversion of secondary alcohols to amides Additionally, the application of this methodology has also been revealed for the synthesis azides directly from their alcohols. Some of the representative examples are shown in the Scheme 4.3 Scheme 4. Direct conversion of alcohols to their azides. Fourth chapter describes highly chemoselective Schmidt reaction. The classical Schmidt reaction involves the formation of new carbon-nitrogen bonds in a reaction of a carbon-centred electrophile with hydrazoic acid followed by loss of nitrogen, which usually occurs via a rearrangement. It is well known that under the Schmidt reaction conditions, ketones and carboxylic acids are converted into their corresponding amides and amines respectively, whereas aldehydes furnish a mixture of formanilides and nitriles. In this chapter, Schmidt reaction of aldehydes to obtain their nitriles without formation of the corresponding formanilide is presented (Scheme 5).4 It was also observed that aromatic ketones and acids functionalities were intact under the reaction condition, unlike the conventional Schmidt reaction. Scheme 5. Highly chemoselective Schmidt reaction Section B It is divided into two chapters, describes a copper catalyzed decarboxylative radical coupling for the synthesis of vinyl sulfones and nitroolefins (Scheme 6). Scheme 6. General strategy for the second part First chapter narrates a strategy for synthesizing nitroolefins from the α,β-unsaturated carboxylic acids. Nitroolefins represent a unique class of nitro compounds, which have multifaceted utility in organic synthesis. They possess antibacterial, rodent-repelling, and antitumor activities. They serve as important intermediates in organic synthesis. Nitroolefins also react with a variety of nucleophiles, and their electron-deficient character renders them as a powerful dienophiles in Diels-Alder reactions. In our attempt to use the decarboxylative strategy, this chapter describes a method for the nitrodecarboxylation of substituted cinnamic acid derivatives to their corresponding nitroolefins. This nitrodecarboxylation reaction is performed using catalytic amount of CuCl in the presence of air using TBN as a nitrating source (Scheme 7).5 Besides, the reaction provides a useful method for the synthesis of β,β-disubstituted nitroolefin derivatives which are generally difficult to access from other conventional methods. Scheme 7. Decarboxylative nitration Second chapter presents a new protocol for the synthesis of vinyl sulfones from the α,β-unsaturated carboxylic acid. Vinyl sulfones are versatile building blocks, which find their utility as Michael acceptors and used in cycloaddition reactions. This functional group has also been shown to potently inhibit a variety of enzymatic processes, and thus provides unique properties for drug design and medicinal chemistry. Vinyl sulfones are prominent in medicinal chemistry owing to their wide presence in pharmaceutically active molecules, such as enzyme inhibitors and biological activity. In this chapter, we report a method for the construction of C-S bonds via ligand promoted decarboxylative radical sulfonylation of ,-unsaturated carboxylic acids to synthesize vinyl sulfones using Cu catalysis (Scheme 8).6 This is the first report for this particular conversion. Scheme 8. Decarboxylative sulfonation

The thesis entitled “Copper-Catalyzed Novel Oxidative Transformations: Construction of Carbon-Hetero Bonds” is divided into two main sections. Section A deals with the utility of azide as a nitrogen source for C-N bond formation, which is further divided into 4 chapters, and section B presents decarboxylative radical coupling reaction for C-heteroatom bond formation which is further divided in to two chapters. Section A Chapter 1 describes an approach for the direct synthesis of nitrile from the corresponding alcohols using azide as a nitrogen source. Nitrile functionality is a versatile and ubiquitous which occurs in a variety of natural products. Nitrile functionality can be easily transformed into a variety of functional groups and products such as aldehydes, ketones, acids, amines, amides and nitrogen-containing heterocycles, such as tetrazoles and oxazoles. In this chapter a successful attempt for developing a novel methodology to oxidize benzylic and cinnamyl alcohols to their corresponding nitriles in excellent yields has been described. This strategy uses DDQ as an oxidant and TMSN3 as a source of nitrogen in the presence of a catalytic amount of Cu(ClO4)2·6H2O. A few representative examples are highlighted in Scheme 1.1 Scheme 1. Oxidative conversion of alcohols to nitriles Second chapter represents a protocol for the synthesis of 1,5-disubstituted tetrazoles from the corresponding secondary alcohols. Among heterocyles, tetrazole and its derivatives are important class of nitrogen containing molecules. Due to their well-known biological activities as well as vast applications in pharmaceuticals and material science, they are potential targets for synthetic organic chemists. Therefore, a simple and user-friendly method for the synthesis of tetrazole is desirable. In this chapter, a mild and convenient method to synthesize 1,5-disubstituted tetrazoles using easily accessible secondary alcohols by employing TMSN3 as a nitrogen source is developed. This reaction is performed in the presence of a catalytic amount of Cu(ClO4)2·6H2O using DDQ as an oxidant under ambient conditions (Scheme 2).2 Scheme 2. Oxidative conversion of secondary alcohols to tetrazoles Third chapter presents a method for synthesizing amides from their corresponding secondary alcohols. Amide functionality is a crucial backbone in peptide chemistry, it also serve as an important precursor or intermediate for variety of organic transformations. In this contention, a mild and convenient method to synthesize amides using easily accessible secondary alcohols by employing TMSN3 as a nitrogen source is developed. This reaction is performed in the presence of a catalytic amount of Cu(ClO4)2·6H2O using DDQ as an oxidant under ambient conditions (Scheme 3).3 Scheme 3. Oxidative conversion of secondary alcohols to amides Additionally, the application of this methodology has also been revealed for the synthesis azides directly from their alcohols. Some of the representative examples are shown in the Scheme 4.3 Scheme 4. Direct conversion of alcohols to their azides. Fourth chapter describes highly chemoselective Schmidt reaction. The classical Schmidt reaction involves the formation of new carbon-nitrogen bonds in a reaction of a carbon-centred electrophile with hydrazoic acid followed by loss of nitrogen, which usually occurs via a rearrangement. It is well known that under the Schmidt reaction conditions, ketones and carboxylic acids are converted into their corresponding amides and amines respectively, whereas aldehydes furnish a mixture of formanilides and nitriles. In this chapter, Schmidt reaction of aldehydes to obtain their nitriles without formation of the corresponding formanilide is presented (Scheme 5).4 It was also observed that aromatic ketones and acids functionalities were intact under the reaction condition, unlike the conventional Schmidt reaction. Scheme 5. Highly chemoselective Schmidt reaction Section B It is divided into two chapters, describes a copper catalyzed decarboxylative radical coupling for the synthesis of vinyl sulfones and nitroolefins (Scheme 6). Scheme 6. General strategy for the second part First chapter narrates a strategy for synthesizing nitroolefins from the α,β-unsaturated carboxylic acids. Nitroolefins represent a unique class of nitro compounds, which have multifaceted utility in organic synthesis. They possess antibacterial, rodent-repelling, and antitumor activities. They serve as important intermediates in organic synthesis. Nitroolefins also react with a variety of nucleophiles, and their electron-deficient character renders them as a powerful dienophiles in Diels-Alder reactions. In our attempt to use the decarboxylative strategy, this chapter describes a method for the nitrodecarboxylation of substituted cinnamic acid derivatives to their corresponding nitroolefins. This nitrodecarboxylation reaction is performed using catalytic amount of CuCl in the presence of air using TBN as a nitrating source (Scheme 7).5 Besides, the reaction provides a useful method for the synthesis of β,β-disubstituted nitroolefin derivatives which are generally difficult to access from other conventional methods. Scheme 7. Decarboxylative nitration Second chapter presents a new protocol for the synthesis of vinyl sulfones from the α,β-unsaturated carboxylic acid. Vinyl sulfones are versatile building blocks, which find their utility as Michael acceptors and used in cycloaddition reactions. This functional group has also been shown to potently inhibit a variety of enzymatic processes, and thus provides unique properties for drug design and medicinal chemistry. Vinyl sulfones are prominent in medicinal chemistry owing to their wide presence in pharmaceutically active molecules, such as enzyme inhibitors and biological activity. In this chapter, we report a method for the construction of C-S bonds via ligand promoted decarboxylative radical sulfonylation of ,-unsaturated carboxylic acids to synthesize vinyl sulfones using Cu catalysis (Scheme 8).6 This is the first report for this particular conversion. Scheme 8. Decarboxylative sulfonation

The thesis presents an unconventional approach for the molecular construction using carbenes as the carbon source, and water as the hydrogen source. A gold-catalyst has been used to transfer the carbenes to effect [2,3]-sigmatropic rearrangement; and tris(pentafluorophenyl)borane-catalyst for the C-C bond functionalization and carbonate transfer reactions. On the other hand, a Pd-catalyzed stereodivergent reduction of alkynes has been achieved using water. The mechanistic details of the hydrogenation have also been probed, and the derived understanding has been applied to construct C-C bonds

The condensation reaction of a primary amine with carbonyl compounds results in a Schiff base, which is effectively incorporated in the preparation of metal complexes. Herein, a series of hetero binuclear complexes have been synthesized of the general formula CuPS.ML, where PS = Schiff base prepared by condensation of salicylaldehyde and propylene diamine; ML = Li, Na or K salts of 2-nitrophenol; 2,4-dinitrophenol; 2,4,6- trinitrophenol & 1-nitroso-2-naphthol. The compounds are generally soluble in most of the organic solvents but insoluble in water. These complexes have been characterized by elemental analysis, IR spectra, UV-VIS spectra, magnetic measurement and molar conductance results. The low value of molar conductance of the complexes suggested the non-electrolyte nature of the complexes. The spectral analysis suggested that the bonding between copper (II) metal chelate and alkali metal, appeared through the dative bond through the phenolic oxygen atoms. The study also revealed the square planar structure of the complexes. Some of these complexes showed the antimicrobial activity on E. coli, S. aureus and C. albicans and so, these complexes may be considered as good antimicrobial agents.

AbstractCopper-catalyzed functionalization of acidic C—H bonds has emerged as a fruitful field due to the abundance and inexpensive nature of copper salts. In this chapter, we summarize the relevant advances in which copper promotes direct C—H functionalizations, including cross-dehydrogenative transformations, of activated organic substrates. The chapter is classified based on the types of activating group, including carbonyl, nitrile, nitro, as well as electron-deficient (hetero)aromatic groups.

This chapter shows, as in previous years, the most important achievements of the 2021 year in the area of organo-phosphorus compounds containing: three P–O bonds (Section 2: phosphoric acids and their derivatives), two P–O and one P–C bonds (Section 3: phosphonic acids and their derivatives) as well as one P–O and two P–C bonds (Section 4: phosphinic acids and their derivatives), in addition to the phosphoryl group P═O, present in all three groups of compounds. Each of the main sections covers “synthesis and reactions” including pure synthesis without applications, “synthesis and biological applications” and “synthesis and miscellaneous applications” including synthesis directed towards non-biological applications. At the end of each subsection, the corresponding achievements are shown for hetero-analogues in which phosphorus–oxygen bonds have been replaced by phosphorus–heteroatom P–X and/or P═Y bonds (X, Y = N, S or Se). The subsection on quinquevalent phosphorus acids and their derivatives as catalysts has been placed, as usual, at the end of the entire chapter, after a review of all three main groups of compounds. As in previous years, the area devoted to phosphoric and phosphonic acids and their derivatives dominated over a smaller section of phosphinic acids and their derivatives, and literature references for these sections remained at a ratio of 4 : 12 : 1. A dynamic, five-fold increase in the number of works, in the subject of chiral phosphoric acids as catalysts, has been recorded in this year.