An epoxide-based approach for polypropionate construction: The synthesis of the ansa chains of streptovaricins D and U

ORGN 226

Wildeliz Torres, wildeliz@hotmail.com, Department of Chemistry, University of Puerto Rico, PO Box 23346, San Juan, PR 00931-3346 and Jose A. Prieto, japrieto@uprrp.edu, Department of Chemistry, University of Puerto Rico at Rio Piedras Campus, PO Box 23346, San Juan, PR 00931-3346.
Streptovaricins are an important class of ansamycin antibiotics that consists of a napthoquinoid core and a polypropionate ansa chain with nine continuous stereogenic centers. Their attractiveness results from their biological activity and the complexity in the elaboration of the chiral centers. For streptovaricin D, the introduction of a carbomethoxy functionality at C10 represents an additional challenge. In order to demonstrate the generality of our epoxide-based methodology for polypropionate construction, we undertook this demanding endeavor. Our reiterative approach consists of three reactions: stereoselective epoxidation of homoallylic alcohols, regioselective alkynylalane cleavage of epoxides, and cis/trans reduction of the incorporated alkyne to produce each propionate unit. Two complementary linear syntheses (C6 to C14 and C14 to C6) were performed, where seven stereogenic centers were constructed in ten synthetic steps.

 

New Reactions and Methodology
1:00 PM-5:00 PM, Monday, 27 March 2006 Georgia World Congress Center -- C301, Oral

Division of Organic Chemistry

The 231st ACS National Meeting, Atlanta, GA, March 26-30, 2006