Cis-Selective Double Spirocyclization via Dearomatization and Isomerization under Thermodynamic Control

J Org Chem. 2023 Feb 3;88(3):1803-1814. doi: 10.1021/acs.joc.2c02225. Epub 2023 Jan 12.

Abstract

Spiro compounds have been considered key scaffolds for pharmaceutical applications. Although many synthetic methods exist for monospirocycles, fewer approaches are known for dispirocycles. Here, we report a highly cis-selective method for constructing a 5/6/5-dispirocyclic structure containing pyrrolidine and γ-lactam rings with various substituents from a series of N-arylpropiolamides. The high cis-selectivity would result from isomerization under thermodynamic control. Cis- and trans-diastereomers can be in equilibrium, favoring cis-adducts.