Copper mediated C-H amination with oximes: en route to primary anilines

Here we report an efficient Cu(i)-mediated C-H amination reaction with oximes as amino donors to introduce NH2 groups directly. Various strongly coordinating heterocycles including quinoline, pyrimidine, pyrazine, pyrazole and triazole were tolerated well. The potential utility was further demonstrated in a late-stage modification of telmisartan (an antagonist for the angiotensin II receptor).

Atom-Economic Silver-Catalyzed Difunctionalization of the Isocyano Group with Cyclic Oximes: Towards Pyrimidinediones

An unprecedented silver-catalyzed difunctionalization of the isocyano group with cyclic oximes is described. This method allows efficient and atom-economic assembly of a vast array of structurally novel and interesting pyrimidinediones, and tolerates a range of functionalities. The resulting products can be easily converted into some useful compounds. Furthermore, the method can also be applied for the late-stage modification of a few biologically active molecules.

Construction of Benzene Rings by Copper-Catalyzed Cycloaddition Reactions of Oximes and Maleimides: An Access to Fused Phthalimides

A useful Cu-catalyzed cycloaddition protocol for the construction of benzene rings has been achieved. The reactions, utilizing readily available oximes and maleimides as starting materials, proceed under mild reaction conditions to generate a series of structurally interesting fused-phthalimides that are difficult to be prepared by conventional methods.

Synthesis of polysubstituted pyridines from oxime acetates using NH4I as a dual-function promoter

An NH₄I dual-function promoter enables pyridine synthesis through oxime N–O bond reduction and subsequent condensation reactions.

Metal-Involving Synthesis and Reactions of Oximes

This review classifies and summarizes the past 10-15 years of advancements in the field of metal-involving (i.e., metal-mediated and metal-catalyzed) reactions of oximes. These reactions are diverse in nature and have been employed for syntheses of oxime-based metal complexes and cage-compounds, oxime functionalizations, and the preparation of new classes of organic species, in particular, a wide variety of heterocyclic systems spanning small 3-membered ring systems to macroheterocycles. This consideration gives a general outlook of reaction routes, mechanisms, and driving forces and underlines the potential of metal-involving conversions of oxime species for application in various fields of chemistry and draws attention to the emerging putative targets.

Oximes and Hydrazones in Bioconjugation: Mechanism and Catalysis

The formation of oximes and hydrazones is employed in numerous scientific fields as a simple and versatile conjugation strategy. This imine-forming reaction is applied in fields as diverse as polymer chemistry, biomaterials and hydrogels, dynamic combinatorial chemistry, organic synthesis, and chemical biology. Here we outline chemical developments in this field, with special focus on the past ∼10 years of developments. Recent strategies for installing reactive carbonyl groups and α-nucleophiles into biomolecules are described. The basic chemical properties of reactants and products in this reaction are then reviewed, with an eye to understanding the reaction's mechanism and how reactant structure controls rates and equilibria in the process. Recent work that has uncovered structural features and new mechanisms for speeding the reaction, sometimes by orders of magnitude, is discussed. We describe recent studies that have identified especially fast reacting aldehyde/ketone substrates and structural effects that lead to rapid-reacting α-nucleophiles as well. Among the most effective new strategies has been the development of substituents near the reactive aldehyde group that either transfer protons at the transition state or trap the initially formed tetrahedral intermediates. In addition, the recent development of efficient nucleophilic catalysts for the reaction is outlined, improving greatly upon aniline, the classical catalyst for imine formation. A number of uses of such second- and third-generation catalysts in bioconjugation and in cellular applications are highlighted. While formation of hydrazone and oxime has been traditionally regarded as being limited by slow rates, developments in the past 5 years have resulted in completely overturning this limitation; indeed, the reaction is now one of the fastest and most versatile reactions available for conjugations of biomolecules and biomaterials.

Cationic N-Heterocyclic Carbene Copper-Catalyzed [1,3]-Alkoxy Rearrangement of N-Alkoxyanilines

The [1,3]-alkoxy rearrangement reactions of N-alkoxyanilines were efficiently catalyzed by cationic N-heterocyclic carbene (NHC)-Cu catalysts in affording 2-alkoxyaniline derivatives in good to excellent yields with high functional group compatibility. For N-alkoxyanilines having an electron-withdrawing substituent at the meta-position, the alkoxy group selectively migrated to the more hindered ortho-position. In contrast, the alkoxy group migrated to the less hindered ortho-position for N-alkoxyanilines having an electron-donating substituent. Mechanistic studies suggest that the rearrangement reactions proceed via an intramolecular route.

Regioselective switching approach for the synthesis of α and δ carboline derivatives

A metal-free protocol for accessing both α and δ-carboline derivatives, starting from a common indolylchalcone oxime ester precursor is reported.

A copper-catalyzed reaction of oximes with diisopropyl azodicarboxylate: an alternative method for the synthesis of oxime carbonates

A Cu-catalyzed protocol is described for the transformation of oximes to the corresponding carbonate derivatives.

Synthesis of enaminones via copper-catalyzed decarboxylative coupling reaction under redox-neutral conditions

A novel copper-catalyzed C(sp³)–H oxidative functionalization of oxime acetates for the synthesis of enaminones under redox-neutral conditions has been developed.

Theoretical prediction of the synthesis of 2,3-dihydropyridines through Ir(iii)-catalysed reaction of unsaturated oximes with alkenes

The Ir(iii)-catalysed reaction of unsaturated oximes with alkenes was predicted, and the results indicate a more efficient synthesis of 2,3-dihydropyridines.

Thiyl radical-mediated cyclization of ω-alkynyl O-tert-butyldiphenylsilyloximes

Treatment of ω-alkynyl O-tert-butyldiphenylsilyloximes with odorless thiol and AIBN gave cyclic O-silylhydroxylamines via a radical process in good yields.

Access to Thiazole via Copper-Catalyzed [3+1+1]-Type Condensation Reaction under Redox-Neutral Conditions

A new strategy for thiazoles via copper-catalyzed [3+1+1]-type condensation reaction from oximes, anhydrides and potassiumthiocyanate (KSCN) is developed herein. The transformation has good functional group tolerance and various thiazoles were formed smoothly in good to excellent yields under mild reaction conditions. This process involves copper-catalyzed N-O/C-S bond cleavages, activation of vinyl sp² C-H bond, and C-S/C-N bond formations which are under redox-neutral conditions as well as operational simplicity.

Visible-light-promoted iminyl radical formation from vinyl azides: synthesis of 6-(fluoro)alkylated phenanthridines

An efficient strategy assisted by visible-light-promoted iminyl radical formation has been developed for the synthesis of 6-(fluoro)alkylated phenanthridine derivatives. In the reactions, addition of alkyl and trifluoromethyl radicals onto vinyl azides gives iminyl radicals, which then undergo intramolecular homolytic aromatic substitution leading to phenanthridines. These reactions can be carried out under mild conditions with high chemical yields and broad substrate scope.