Mild Pd(OAc)2/PPh3 Catalyzed Cyclization Reactions of 2-Vinylazetidines with Heterocumulenes: An Atom-Economy Synthesis of Tetrahydropyrimidinone, Tetrahydropyrimidinimine, and Thiazinanimine Analogs
作者:Gyro A. Inman、David C. D. Butler、H. Alper
DOI:10.1055/s-2001-14665
日期:——
A versatile method for the reaction of N-alkyl-2-vinylazetidines with heterocumulenes has been established using a Pd(OAc)2/PPh3 catalyst system at room temperature. Minor modifications in the design of either substrate allowed for the optimization of product yield. Evidence for Ï-allylpalladium formation was obtained from the reaction of trans-1-butyl-4-methyl-2-vinylazetidine, which afforded a cis/trans mixture of products arising from stereochemical inversion through η 3-η 1-η 3 isomerization.
Synthesis of Eight‐Membered Lactams through Formal [6+2] Cyclization of Siloxy Alkynes and Vinylazetidines
作者:An Wu、Qiang Feng、Herman H. Y. Sung、Ian D. Williams、Jianwei Sun
DOI:10.1002/anie.201902866
日期:2019.5.13
lactams through formal [6+2] cyclization of siloxyalkynes and vinylazetidines has been developed. Evidence from a chirality transfer experiment suggests that the reaction proceeds via a [3,3]‐sigmatropic rearrangement from a ketene 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.