ENANTIOSELECTIVE ROUTE TO THREO 8.0.4'-TYPE NEOLIGNANS - SYNTHESIS OF(-)-VIROLIN

A combination of diastereoselective borohydride reduction of the subst ituted alpha-bromo-propiophenone [(+/-)-2] and microbial-assisted hydr olysis of its corresponding bromohydrin acetate using Rhizopus nigrica ns, led to the chiral epoxide, (-)-6. The regiospecific opening of thi s epoxide, produced pure (-)-virolin [1], whose absolute configuration could be assigned through this sequence as 7S,8S. It is possible, by selecting the appropriate starting materials, to obtain different chir al three neolignans of the 8.0.4'-type and to predict their configurat ion.