A Cycloaddition Protocol for the Assembly of the Hexacyclic Framework Associated with the Kopsifoline Alkaloids

• Authors: Xuechuan Hong, Emory University; Stefan France, Emory University; Jose M. Mejia-Oneto, Emory University; Albert Padwa, Emory University
• Journal Title: Organic Letters
• Volume: Volume 8, Number 22
• Publisher: American Chemical Society | 2006-10-26, Pages 5141-5144
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1021/ol062029z
• Subjects: Chemistry, General

Abstract

An approach to the hexacyclic framework of the kopsifoline alkaloids has been developed and is based on a Rh(II)-catalyzed cyclization-cycloaddition cascade. The resulting [3+2]-cycloadduct was readily converted into the TBS enol ether 23. Oxidation of the primary alcohol present in 23 followed by reaction with CsF afforded compound 24 that contains the complete hexacyclic skeleton of the kopsifolines.