Enantioselective synthesis of imperanene, a platelet aggregation inhibitor

Both enantiomers of imperanene, a platelet aggregation inhibitor, have been synthesized in 82-90% ee. The key step of establishing the chiral center was achieved through stereoselective alkylation with benzyl chloromethyl ether using Enders' RAMP/SAMP chiral auxiliary method. The natural product was determined to be the (S)-enantiomer through comparison of optical rotation data. Reaction: see text.