Letteratura scientifica selezionata sul tema "Aza-Wacker"

A palladium(ii)-catalyzed intramolecular oxidative aza-Wacker-type reaction of vinyl cyclopropanecarboxamides to access a series of conformationally restricted highly substituted aza[3.1.0]bicycles is reported.

AbstractOver the past years, Pd(II)-catalyzed oxidative couplings have enabled the construction of molecular scaffolds with high structural diversity via C–C, C–N and C–O bond-forming reactions. In contrast to the use of stoichiometric amounts of more common oxidants, such as metal salts (Cu and Ag) and benzoquinone derivatives, the use of molecular oxygen for the direct or indirect regeneration of Pd(II) species presents itself as a more viable alternative in terms of economy and sustainability. In this review, we describe recent advances on the development of Pd-catalyzed oxidative cyclizations/functionalizations, where molecular oxygen plays a pivotal role as the sole stoichiometric oxidant.1 Introduction2 Oxidative C–C and C–Nu Coupling2.1 Intramolecular Oxidative C–Nu Heterocyclization Reactions2.1.1 C–H Activation2.1.2 Wacker/Aza-Wacker-Type Cyclization2.1.3 Tandem Wacker/Aza-Wacker and Cyclization/Cross-Coupling Reactions2.2 Intermolecular Oxidative C–Nu Heterocoupling Reactions2.3 Intramolecular Oxidative (C–C) Carbocyclization Reactions2.4 Intermolecular Oxidative C–C Coupling Reactions2.4.1 Cyclization Reactions2.4.2 Cross-Coupling Reactions2.4.3 Homo-Coupling Reactions3 Aerobic Dehydrogenative Coupling/Functionalization4 Oxidative C–H Functionalization5 Summary

Electrochemical or photochemical single-electron oxidation of bench-stable substrates can generate radical cations that offer unique reactivities as intermediates in various bond-formation processes. Such intermediates can potentially take part in both radical and ionic bond formation; however, the mechanisms involved are complicated and not fully understood. Herein, we report electrochemical radical cation aza-Wacker cyclizations under acidic conditions, which are expected to proceed via radical cations generated by single-electron oxidation of alkenes.

The discovery of an unprecedented 1,2-aryl migratory process in Pd(ii)-catalyzed aza-Wacker-type cyclization of 2-alkenylanilines that led to a novel synthesis of C3-substituted indoles is demonstrated.

A novel and practical organoselenium-catalyzed, N¹- and N²-selective controllable aza-Wacker reaction is realized, which provides an easy access to N¹- and N²-olefinated benzotriazole derivatives.

An efficient approach for the organoselenium-catalyzed aza-Wacker reaction of olefinic hydrazones and an oxime to form isoquinolinium imides and an isoquinoline N-oxide is developed. This transformation involves a direct intramolecular C–H amination using hydrazones and an oxime as imine-type nitrogen sources. This work not only provides a new approach for the construction of isoquinoline derivatives, but also expands the scope of nitrogen sources in electrophilic selenium catalysis.

Les 3-amino-3-désoxyglycosides (ADGi) constituent une classe essentielle de glycosides, présents dans la structure de nombreux composés bioactifs importants. Les 3-amino-3-désoxyglycals (ADGa) sont des donneurs prometteurs pour la synthèse de ces ADGi. La partie glycal des ADGa permet de les envisager à la fois comme donneurs de 2-désoxy-ADGi par glycosylation en présence d’un accepteur, ou de 1,2-trans-ADGi via une séquence époxydation/glycosylation. Ces travaux de thèse ont été consacrés au développement d’une nouvelle voie d’accès à ces ADGa, mettant à profit deux réactions clés : un réarrangement de Ferrier, suivi d’une réaction d’aza-Wacker (AW) en conditions oxydantes avec un lien amovible de type carbamate. Cette réaction d’AW permet, en une seule étape, de former la liaison C3-N et de regénérer le glycal. En modifiant des conditions issues de la littérature utilisant la 1,4-benzoquinone (p-BQ), nous avons obtenu les ADGa correspondant aux séries D-Glucal, D-Galactal, L-Rhamnal et L-Fucal, en utilisant le DMF comme solvant. Les ADGa étant obtenus avec des protections orthogonales, une preuve de concept de leur déprotection sélective a pu être réalisée sur l’ADGa modèle. Finalement, l’ADGa dérivé du D-Galactal a été engagé dans une séquence d’époxydation / glycosylation pour la synthèse d’un disaccharide avec d’excellents rendements et sélectivités. L’utilisation du DMF comme solvant nous a ensuite permis de définir des conditions pour cette cyclisation d’AW en utilisant le dioxygène de l’air comme réoxydant du Pd (0). La sélectivité de l’étape d’amidopalladation a également été étudiée pour les deux systèmes. Après deutération des adduits de Ferrier, nous avons démontré que l’amidopalladation était trans dans les deux systèmes réoxydants, en partant des carbamates dérivés du D-Glucal et du D-Galactal. Finalement, deux sous-produits d’intérêts ont pu être étudiés. Le premier, obtenu lors de l’optimisation avec la p-BQ, correspond formellement à une fonctionnalisation 1,3 du carbamate modèle, et ses conditions de synthèse ont été optimisées. Le second est un dérivé d’hexa-2,4-diènal, qui a pu être isolé et pleinement caractérisé
3-Amino-3-deoxyglycosides (ADGi) constitute an essential class of glycosides found in the structure of several important bioactive compounds. 3-Amino-3-deoxyglycals (ADGa) are promising donors for these ADGi. The glycal moiety allows ADGa to serve as donors of 2-deoxy-ADGi by glycosylation in the presence of an acceptor, or as donors of 1,2-trans-ADGi through an epoxidation / glycosylation sequence. This thesis work focuses on developing a new synthetic route for these ADGa, taking advantage of two key reactions: a Ferrier reaction followed by an aza-Wacker (AW) reaction in oxidizing conditions with carbamate type tether. This AW step enables C3-N bond formation and glycal reformation in a single step. Based on modified conditions from the literature using 1,4-benzoquinone (p-BQ), we obtained ADGa corresponding to the D-Glucal, D-Galactal, L-Rhamnal, and L-Fucal series, using DMF as the solvent. These ADGa were obtained orthogonally protected, and a proof of concept for their selective deprotection was demonstrated on the model ADGa. Finally, the ADGa derived from D-Galactal was subjected to an epoxidation / glycosylation sequence to synthesize a disaccharide with excellent yield and selectivity. The use of DMF as a solvent also allowed us to establish conditions for the AW cyclization, using dioxygen from the air as a reoxidant for Pd(0). The selectivity of the amidopalladation step was then examined for the two systems. After deuteration of the Ferrier adducts, we demonstrated that amidopalladation proceeded trans in both reoxidizing systems, starting from carbamates derived from D-Glucal and D-Galactal. Finally, two by-products of interest were studied. The first is a formal 1,3-functionalization of the model carbamate, and the reaction conditions for its synthesis were optimized. The second is a hexa-2,4-dienal derivative, which was isolated and fully characterized