In comparison to previous reviews, the present review article provides a comprehensive survey of Ritter reactions from 2014 to 2020, mainly aiming to discuss diverse Ritter reactions and their widely...

A novel tandem oxidative Ritter reaction/hydration/aldol condensation of α-arylketones with substituted propiolonitriles has been developed. This protocol conveniently affords a wide range of functionalized 3-acyl-3-pyrrolin-2-ones through the efficient construction of four chemical bonds, a C–N bond, a CC bond, and two CO bonds, and the formation of one ring bearing an aza-quaternary center, which is ascribed to the strategical introduction of functionalized nitriles to this transformation. A reaction mechanism was proposed based on some control experiments.

Although the classical Ritter reaction has been widely applied to prepare sterically hindered amides since 1948, it has intrinsic problems, such as harsh reaction conditions, the multistep preparation of synthetic precursors, and the use of solvent quantities of nitrile. In particular, only a few examples of the total syntheses of natural products using the Ritter reaction as a key step have been reported to date. In this article, an oxidative Ritter-type reaction of α-arylketones was developed to efficiently construct a sterically hindered N-acyl aza-quaternary carbon moiety. The current transformation features the use of 10 equivalents of nitriles, a broad substrate scope (81 examples), a short reaction time, and mild reaction conditions; notably, both of the use of a limited amount of nitriles and the producing carbocation intermediates via the C-H bond oxidation strategy address two intractable problems of the classical Ritter reaction. Furthermore, based on an unprecedented synthetic strategy using this oxidative Ritter reaction to construct a C-5 aza-quaternary carbon center, the collective total syntheses of erythrina alkaloids, including erysotramidine, 11-α-methoxyerysotramidine, 11-β-hydroxyerysotramidine, erytharbine, the proposed 11-βmethoxyerysotramidine and 10,11-dioxoerysotramidine, and the unnatural 11-α-hydroxyerysotramidine, have been completed using a common precursor through a one-step chemical transformation.