Cleavage of epoxides with functionalized alkynylaluminum reagents

CHED 412

Keyla F Morales, keylapr_13@hotmail.com, Danisha M Rivera, danita_8@hotmail.com, Jose A. Prieto, and Gerardo Torres. Department of Chemistry, University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, San Juan, PR 00931
Polypropionates are a common feature of many macrolide natural products. They consist of an array of alternating methyl and hydroxy groups on an aliphatic chain with a particular configuration. We have developed an epoxide-based methodology for the construction of polypropionates, consisting of a reiterative sequence of steps. Our approach involves a regioselective epoxide cleavage with an alkynyl aluminum reagent, reduction of the alkyne, and the stereoselective epoxidation of the resulting alkene for the elaboration of each propionate unit. The reaction of 3-O-substituted propynyl aluminum reagents with TIPS-protected 2,3-epoxy alcohols offers a convenient synthetic approach for the subsequent preparation and epoxidation of allylic alcohols. This stereoselective method provides a series of new anti 3,4-epoxy alcohols not previously accessible and expands the scope of our epoxide-based methodology. The experimental results of this investigation will be presented. Work was supported by NIH SCORE (2S06GM-0810-29) and RISE (2R25GM061151) Programs.