Pericyclic reactions in nature: Synthesis and Cope rearrangement of thermolabile bis-alkenylcyclopropanes from female gametes of marine brown algae (Phaeophyceae)
作者:Georg Pohnert、Wilhelm Boland
DOI:10.1016/s0040-4020(97)00886-7
日期:1997.10
The biosyntheses of the 6-substituted cyclohepta-1,4-dienes dictyotene (1), ectocarpene (2), desmarestene (3), vinylcycloheptadiene (4) and lamoxirene (5) involve a spontaneous Cope rearrangement of thermolabile bis-alkenylcyclopropane precursors like 16, 10, 26 and 30. The unstable precursors and the rearranged cycloheptadienes were synthesised from the chiral 2-iodovinylcyclopropane 12 using Pd-0 or Cu-1 catalysed approaches. Activation parameters of the Cope rearrangements were determined. Bioassays with pre-ectocarpene 10 established the thermolabile cyclopropane (1R,2R)-10, rather than the cyclohepta-1,4-diene(6S)-2, as the genuine pheromone of the brown alga Ectocarpus siliculosus. (C) 1997 Elsevier Science Ltd.