Chemoselective CC Bond Cleavage of Epoxide Motifs: Gold(I)-Catalyzed Diastereoselective [4+3] Cycloadditions of 1-(1-Alkynyl)oxiranyl Ketones and Nitrones
作者:Tao Wang、Junliang Zhang
DOI:10.1002/chem.201002395
日期:2011.1.3
Cutting carbon! A novel facile strategy for the CCbondcleavage of oxiranylketones has been developed. Carbophilic gold(I) activation of the alkyne side chain mediates a heterocyclization and subsequent CCbondcleavage (see scheme).
Chiral N,N′-dioxide-Sc(NTf<sub>2</sub>)<sub>3</sub> complex-catalyzed asymmetric bromoamination of chalones with N-bromosuccinimide as both bromine and amide source
A chiral N,N[prime or minute]-dioxide-Sc(NTf2)3complex catalytic system has been developed to catalyze the asymmetric bromoamination reaction of chalones with N-bromosuccinimide.
A new Michael-initiated cyclopropanation reaction using alpha-bromochalcones as Michael acceptor was developed. Compared to previous works using arylidenemalonates as Michael acceptor, this novel protocol could improve the synthesis of trans-isomers of diethyl 2-benzoyl-3-phenyl-cyclopropane-1,1-dicarboxylates. More importantly, this method also provided the first access to the cis-isomers of these densely substituted cyclopropanes with the Michael-initiated ring closure (MIRC) strategy, albeit with a poor diastereoselectivity. (C) 2013 Published by Elsevier Ltd.