Silver‐Catalyzed [3+2] Cycloaddition for the Diastereoselective Synthesis of anti‐3‐Substituted Hydroindolin‐2‐Imines

Abstract

We describe a silver catalyzed [3 + 2] diastereoselective annulation of p-quinamines and ketenimine zwitterionic salts, leading to anti-3substituted hydroindolin-2-imines under mild conditions. Ketenimine zwitterionic salts participate in the [3 + 2] cycloadditions as a monoolefin (2πsystem). The relative stereoselectivity of the reaction was regulated by the tert-butyl ester. This protocol is complementary to the synthesis of functionalized hydroindoles moiety and expands the application of ketenimine zwitterionic salts.

An Oxidant-Free and Mild Strategy for Quinazolin-4(3H)-One Synthesis via CuAAC/Ring Cleavage Reaction

“…It has also been used for modifying the structure of natural products, drugs, and biological macromolecules [42][43][44]. Our group has delved into this area and utilized the CuAAC/ring cleavage reaction to synthesize pyridine derivates, fused heterocycles, coumarins, indoles, and other nitrogenated compounds [45][46][47][48][49].…”

Asymmetric Synthesis of Hydroindoles via Desymmetrizing [3+2] Annulation of p-Quinamines and Arylalkylketenes

“…The hydroindole skeleton is widely present in various natural polycyclic alkaloids and drug molecules, such as acutumine, mesembrine, thelepogine, and tazettine (Scheme a) . Even though many synthesis strategies for hydroindole frameworks have been developed on the basis of p -quinamine substrates, the asymmetric catalytic method was still less developed . Chiral amine organocatalysts have been successfully applied to promote asymmetric formal cyclization of p -quinamines and the analogues, with a particular role in covalent bond activation of the partners .…”