A new synthetic approach to the polyoxins: Concise stereoselective preparation of protected thymine polyoxin C

A new approach to the synthesis of thymine polyoxin C has been devised, which uses the prochiral ketone 8-oxabicyclo[3.2.1]octan-3-one 8 as the starting material. An enol silane 12 derived from this ketone was reacted with TsN=Se=NTs in order to install the nitrogen functionality required in die final product whilst retaining a reactive C=C in the product 13. This compound was cleaved using ozone lid, following protecting group manipulation, was subjected to an unusual one carbon side-chain degradation employing Pb(OAc)(4) to give an appropriate glycosyl donor 25. Completion of the synthesis of a protected thymine polyoxin C was then carried out by reaction of 25 under Vorbruggen conditions. (C) 1997 Elsevier Science Ltd.