SYNTHESES OF (+)-(S,S)-(CIS-6-METHYLTETRAHYDROPYRAN-2-YL)ACETIC ACID AND OF (-)-(R,R)-DIDESOXY-PYRENOPHORINE USING A NEW D5-REAGENT

The Li/K‐derivative 6 is used to synthesize the title compounds (3a and 4a) in enantiomerically pure form from (−)‐(S)‐propylene epoxide. The C,C bond forming key step leading to the hydroxyketone 7 is followed by cyclization (→, 8), Beckmann cleavage (→ 9b) and hydrolysis to 3a (recently isolated from civet). Base treatment of 3a opens the ring (10) to give the hydroxyacid 1 which is cyclized to the macrolide 4a. The synthetic usefulness of the highly nucleophilic doubly reduced dienone system 6 as d5‐reagent (see synthons 2) is thus demonstirated. Copyright © 1979 Verlag GmbH & Co. KGaA, Weinheim