Recent Progress in Chromium-Mediated Carbonyl Addition Reactions

Abstract

AbstractOrganochromium(III) species are versatile nucleophiles in complex molecule synthesis due to their high functional group tolerance and chemoselectivity for aldehydes. Traditionally, carbonyl addition reactions of organochromium(III) species were performed through reduction of organohalides either using stoichiometric chromium(II) salts or catalytic chromium salts in the presence of stoichiometric reductants [such as Mn(0)]. Recently, alternative methods emerged involving organoradical formation from readily available starting materials (e.g., N-hydroxyphthalimide esters, alkenes, and alkanes), followed by trapping the radical with stoichiometric or catalytic chromium(II) salts. Such methods, especially using catalytic chromium(II) salts, will lead to the development of sustainable chemical processes minimizing salt wastes and number of synthetic steps. In this review, methods for generation of organochromium(III) species for addition reactions to carbonyl compounds, classified by nucleophiles are described.1 Introduction2 Alkylation2.1 Branch-Selective Reductive Alkylation of Aldehydes Using Unactivated Alkenes2.2 Linear-Selective Alkylation of Aldehydes2.2.1 Catalytic Decarboxylative Alkylation of Aldehydes Using NHPI ­Esters2.2.2 Catalytic Reductive Alkylation of Aldehydes Using Unactivated Alkenes2.2.3 Alkylation of Aldehydes via C(sp3)–H Bond Functionalization of Unactivated Alkanes2.3 Catalytic α-Aminoalkylation of Carbonyl Compounds3 Allylation3.1 Catalytic Allylation of Aldehydes via Three-Component Coupling3.2 Catalytic Allylation of Aldehydes via C(sp3)–H Bond Functionalization of Alkenes4 Propargylation: Catalytic Propargylation of Aldehydes via Three-Component Coupling5 Conclusion