A gold-catalyzed intermolecular reaction of propiolic acids with alkenes led to a [4 + 2] annulation or enyne cross metathesis. The [4 + 2] annulation proceeds with net cis-addition with respect to alkenes and provides an expedient route to α,β-unsaturated δ-lactones, for which preliminary asymmetric reactions were also demonstrated. For 1,2-disubstituted alkenes, unprecedented enyne cross metathesis
Au(i)-catalyzed intramolecular oxidative cyclopropanation of 1,6-enynes derived from propiolamides with diphenyl sulfoxide
作者:Hyun-Suk Yeom、Seunghoon Shin
DOI:10.1039/c2ob27394b
日期:——
We have developed gold(I)-catalyzedoxidativecyclopropanation of 1,6-enynes derived from propiolamides employing diphenyl sulfoxide as an oxidant. 1,6-Enynes having a terminal alkyne and a propiolamide tether efficiently transformed into cyclopropane carboxaldehyde derivatives.
(Z)-beta-lodo-propenamides and -beta-iodo-propenoic esters were selectively prepared in high yields, at room temperature, through reaction of 2-propynamides and 2-propynoic esters, respectively, with AlCl3 and Nal in the presence of t-BuOH in dichloromethane. These experimental conditions are compatible with the presence of acid sensitive acetal groups. Alternative use of EtOH or H2O in place of t-BuOH was investigated. (Z)-Bromo-propenamides and corresponding esters were prepared according to a similar procedure using sodium bromide in refluxing acetonitrile. (C) 2009 Published by Elsevier Ltd.