Switchable Diastereoselectivity in the Fluoride-Promoted Vinylogous Mukaiyama–Michael Reaction of 2-[(Trimethylsilyl)oxy]furan Catalyzed by Crown Ethers
作者:Giorgio Della Sala、Marina Sicignano、Rosaria Schettini、Francesco De Riccardis、Luigi Cavallo、Yury Minenkov、Chloé Batisse、Gilles Hanquet、Frédéric Leroux、Irene Izzo
DOI:10.1021/acs.joc.7b00743
日期:2017.7.7
Mukaiyama–Michael reaction of 2-[(trimethylsilyl)oxy]furan with diverse α,β-unsaturated ketones is described. The TBAF-catalyzed VMMR afforded high anti-diastereoselectivity irrespective of the solvents used. The KF/crown ethers catalytic systems proved to be highly efficient in terms of yields and resulted in a highly diastereoselective unprecedented solvent/catalyst switchable reaction. Anti-adducts
描述了氟化物促进的2-[((三甲基甲硅烷基)氧基]呋喃与不同的α,β-不饱和酮的乙烯基类的Mukaiyama-Michael反应。的TBAF催化VMMR得到高抗不管所用溶剂的-diastereoselectivity。KF /冠醚催化体系在产率方面被证明是高效的,并且导致了高度非对映选择性的空前的溶剂/催化剂可转换反应。当在CH 2 Cl 2中使用苯并-15-冠-5时,获得的抗加合物为单一非对映异构体或具有优异的非对映选择性。另一方面,高同步-非对映选择性(从73:27至96:4)是通过在甲苯中使用二环己烷-18-冠-6实现的。在DFT计算的基础上,提出了与催化剂/溶剂有关的可转换非对映选择性,这是由于松散或紧密的阳离子-二壬酸酯离子对的结果。