Dityltin bis(triflate) is a mild Lewisacid which catalyzes clean Michael addition of enol silylethers. The new catalyst allows to employ various labile acceptors such as methyl vinyl ketone and 2-cyclopentenone which do not undergo smooth reaction with conventional Lewisacids. A variety of enol silylethers are also employable and thus 2-(trimethylsiloxy)propene, the simplest one in this class of
In this report, a generalmethod for the preparation of 1,5-dicarbonyl compounds and six membered ring annelation is described. This method involves the reaction of hemiacetal vinylogs 1 with enol ethers 2 or 3 in the presence of a Lewis acid. This reaction was successfully applied to the enol ethers of α and α,α'-hindered ketones such as 2,2,6-trimethyl cyclohexanone. α-Cyperone and 6-epi-α-cyperone
A total synthesis of the sesquiterpene quinone metachromin-A
作者:Wanda P. Almeida、Carlos Roque D. Correia
DOI:10.1016/s0040-4039(00)76220-4
日期:1994.2
The first totalsynthesis of the marine natural product metachromin A was accomplished through a convergent synthesis amenable to the preparation of synthetic analogues. The main features of this synthesis are the introduction of the oxygenation at C17 employing a Thiele acetoxylation reaction and a stereoselective Horner-Wadsworth-Emmons coupling of a nonstabilized phosphonate with a methyl ketone