Synthesis and expansion of bicyclic enol ether: a probable precursor for the synthesis of macrolide (±)-pyrenophorin

A convenient procedure for the synthesis and expansion of bicyclic rings has been developed for the production of probable precursors of non-racemic pyrenophorin, an antibiotic dilactone. The major highlight for this new synthetic methodology came from the use of a readily available reagent of easy manipulation, 9-oxabicyclo[3.3.1]nonane-2,6-diol, for the preparation of the bicyclic intermediate, which sequentially was subjected to oxidative cleavage with butyl nitrite resulted in an isomeric mixture, a dioximedilactone and diisoxazoledilactone