First asymmetric total synthesis of (-)-(R)- and (+)-(S)-geibalansine

Treatment of prochiral chromenoquinoline 2 with (R,R)- and (S, S)-(1,4-di-tert-butyl-salicilydene)-diaininocycloilexane (manganese 111) chloride, and buffered house bleach (pH - 11) gave the epoxide 3 with 90-95% yield and ee >93% (estimated by polarimetry). The epoxides were opened with H-2 Pd/C 10% affording geibalansine 1 in 75% yield and ee 94-98%, determined by HPLC analysis. (C) 2003 Elsevier Ltd. All rights reserved.