Trimethylsilyltriflate-Promoted Addition of 2-Trimethylsilyloxyfuran to a Chiral Cyclic Nitrone; a Short Synthesis of [1S(1α,2β,7β,8α,8aα)]-1,2-Di(t-butyldiphenylsilyloxy)-indolizidine-7,8-diol

The trimethylsilyl triflate promoted addition of 2-trimethylsilyloxyfuran to (3S,4S)-3,4-dihydro-3,4-di(t-butyldiphenylsilyloxy)-2H-pyrrole 1-oxide, derived from (R,R)-tartaric acid, displays complete facial selectivity, affording two diastereomeric butenolides in excellent overall yield. The major adduct undergoes silica-gel induced ring-closure to give in almost quantitative yield [4S(4α,5β,5aβ,5bα,8aα)]-hexahydro-4,5-di(t-butyldiphenylsilyloxy)-pyrrolo [1,2-b]furo[2,3d] isoxazol-7(3H)one; reduction with DIBAH followed by hydrogenolysis on Pd(OH)2/C affords the partially protected 1,2,7,8-indolizidinetetrol.