Herein, a copper­(I)-catalyzed alkynylogous Mannich-type reaction is developed, which starts from pyrazoleamides of alkynyl-substituted acetic acids and provides an array of chiral α-allenylamine derivatives in high regio-, diastereo-, and enantioselectivities. This reaction enjoys broad substrate scopes on both pyrazoleamides and N-Boc-aldimines. Moreover, a copper­(I)-catalyzed cascade cyclization of pyrazoleamides of but-2-ynoic acid is disclosed, which involves an α-selective Mannich-type reaction as a key step and delivers a series of chiral β-lactams containing a pyrazole moiety in high enantioselectivity. In light of some mechanism studies, the deprotonation step is found as the rate-determining step in this cyclization. Propargyl copper­(I) species are proposed as the operating nucleophiles in both reactions. Finally, the synthetic utility of the alkynylogous product is demonstrated by the transformations of the product to chiral α,β-unsaturated lactones. Furthermore, a gram-scale preparation of chiral β-lactam and its following transformations proved its synthetic versatility.

Main observation and conclusion A general synthesis of chiral 1,3‐disubstituted allylsilanes is established through copper(I)‐catalyzed asymmetric 1,4‐conjugate silylation of α,β‐unsaturated sulfones and subsequent Julia‐Kocienski olefination. By modification of McQuade's NHC ligand, the catalytic asymmetric conjugate silylation with a broad substrate scope is achieved in high enantioselectivity. The following Julia‐Kocienski olefination proceeds smoothly at room temperature to deliver an array of chiral allylsilanes in moderate yields. More interestingly, a one‐pot asymmetric synthesis with high synthetic efficiency is successfully realized. Utility of the prepared chiral 1,3‐disubsituted allylsilanes is demonstrated in the asymmetric allylation of both aldehyde and aldimine. Finally, an interesting “match and mismatch” phenomenon is observed in the asymmetric allylation of chiral aldehydes.