Synthesis of Eight‐Membered Lactams through Formal [6+2] Cyclization of Siloxy Alkynes and Vinylazetidines

Abstract

An ew approachf or the efficient synthesis of eightmembered lactams through formal [6+ +2] cyclization of siloxy alkynes and vinylazetidines has been developed. Evidence from ac hirality transfer experiment suggests that the reaction proceeds via a[3,3]-sigmatropic rearrangement from aketene intermediate.This insight led to the development of alternative conditions and use of acyl chlorides as ketene precursors for the [6+ +2] reaction with vinylazetidines.

A Dipolar Cyclization/Fragmentation Strategy for the Catalytic Asymmetric Synthesis of Chiral Eight-Membered Lactams

“…To our knowledge, this kind of medium-sized heterocycles are popular scaffolds in many biologically active agents as exemplified in Figure 2a. [55][56][57][58][59][60] Though impressive synthetic endeavors, the catalytic asymmetric synthesis starting from easily available feedstocks are still very rare. [61][62][63] As depicted in Figure 2b, the detailed design plan consisted of two catalysis cycles.…”

Designing and Accurately Developing a [6 + 2] Dipolar Cycloaddition for the Synthesis of Benzodiazocines

“…(1) [6 + 2] dipolar cycloadditions are limited by entropic effects, enthalpic effects, and transannular steric interactions 11 and ( 2) competition between intermolecular cycloaddition and intramolecular cycloaddition under Brønsted base catalysis, 12 which always requires the use of a high dilution (typically at the micromolar level) or the slow addition of substrates.…”