A CONCISE SYNTHESIS OF (E)-NEOMANOALIDE AND (Z)-NEOMANOALIDE

The first synthesis of(Z)-neomanoalide (4) and an improved synthesis of its (E)-isomer 3 was accomplished in a concise, regiocontrolled manner by exploiting 2-[(tert-butyl)dimethylsiloxy]-4{[(tert-butyl)dimethylsiloxy]- methyl}furan (6) as the key reagent. Lithiation of 6 and subsequent reaction with the (2Z)- or (2E)-isomer of (6E)-3-{[(tert-butyl)dimethylsiloxy]methyl}-7-methyl-9-(2',6',6'-trimethylcyclohex-1'-enyl)nona-2,6-dienyl bromide (5), followed by hydrolysis, afforded the corresponding neomanoalide.