CHIRAL ETA(6)-ARENE-CR(CO)(3) COMPLEXES AS SYNTHETIC BUILDING-BLOCKS - AN ENANTIOSELECTIVE AND DIASTEREOSELECTIVE APPROACH TO SUBSTITUTED HYDROPHENALENES RELATED TO HELIOPORIN-E AND PSEUDOPTEROSIN-G

The enantioselective total synthesis of compound 14, an analogue of di hydro-helioporin E and dihydro-pseudopterosin G, is accomplished by a strategy which centrally relies on the reactivity of arene-Cr(CO)(3) c omplexes. The chiral synthetic building block 6 (> 97 % e.e.) is conve rted in 12 steps regio- and diastereoselectively into complex 12, from which 14 is obtained by decomplexation and methylation. Key steps of the synthesis are two succesive regio- and diastereoselective benzylic deprotonation/alkylation reactions.