American Chemical Society
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Indolyl-oxazaphosphorine Precursors for Stereoselective Synthesis of Phosphite Triesters and Dithymidinyl Phosphorothioates

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journal contribution
posted on 1999-10-14, 00:00 authored by Jian-Chao Wang, George Just
Several novel chiral indolyl-oxazaphosphorines 7 were synthesized, and their potential as precursors to chiral phosphorothioates was evaluated. Reaction of 7 with a thymidine derivative gave phosphite triester 8 with a large degree of stereoselectivity. Sulfurization with Beaucage's reagent provided phosphorothioate triesters 9. The chiral auxiliary 9b containing a cyano group could be easily removed with aqueous ammonia to form dithymidinyl phosphorothioate in more than 97% diastereomeric excess. The chiral indolyl-oxazaphosphorines 7 are a new class of precursors for stereoselective synthesis of phosphorothioates.