Abstract Treatment of the acyclic tetraenols (E)-and (Z)-2 with an excess of ClSO 3 H in 2- nitropropane at− 80 stereoselectively afforded in 30 and 43% yield, respectively, diastereoisomer mixtures of the racemic, tricyclic ethers 1c, d and 1a, b, together with 20 (Table). Under identical conditions, but with the acyclic pentaenol 10 (1: 1 diastereoisomer mixture) as substrate, the tricyclic ethers 22a/22b (10: 1) were isolated in 27% yield. These ...
