A Short Total Synthesis of (±)-Epimeloscine and (±)-Meloscine Enabled by a Cascade Radical Annulation of a Divinylcyclopropane
摘要:
The first stereoselective synthesis of epimeloscine has been accomplished in 13 total steps with a longest linear sequence of 10 steps. The core of the synthesis takes only five steps, the key ones being acylation, stereoselective tandem radical cyclization of a divinylcyclopropane to make two rings, and group-selective ring-closing metathesis of the resulting divinylcyclopentane to make the last ring.
Highly functionalized donor–acceptor cyclopropanes applied toward the synthesis of the Melodinus alkaloids
摘要:
A series of highly substituted vinylcyclopropanes were prepared and examined as reaction partners in a palladium-catalyzed (3+2) cycloaddition with nitrostyrenes. Described herein are our efforts to synthesize an elusive 1,1-divinylcyclopropane by several distinct approaches, and to apply surrogates of this fragment toward the synthesis of the Melodious alkaloids. (C) 2014 Elsevier Ltd. All rights reserved.