TOTAL SYNTHESIS OF (1S,4S)-7,8-DIHYDROXYCALAMENENE VIA BENZYLIC ALKYLATION OF ETA(6)-ARENE-CR(CO)3 COMPLEXES

The enantioselective total synthesis of the antiinfective sesquiterpen e (1S,4S)-7,8-dihydroxycalamenene (4) is accomplished by a strategy wh ich centrally utilizes the reactivity of arene-Cr(CO)3 complexes. In a sequence involving two successive benzylic deprotonation/alkylation s teps, the chiral complex 8 (> 99 % e.e.) is converted completely regio - and diastereoselectively to 7 and further by decomplexation and ethe r cleavage to the target compound 4 in high overall yield and without loss of enantiomeric purity.