Pericyclic Reactions in Nature: Spontaneous Cope Rearrangement Inactivates Algae Pheromones

摘要

Female gametes of marine brown algae use olefinic C_(11) hydrocarbons as chemical signals to trigger the release of and or attract conspecific flagellated motile male sex cells. In 1971 Miiller et al. isolated ectocarpene (2a), the pheromone of the cosmopolitan brown algae Ectocarpus ailiculosus. It soon proved to be the prototype of a whole series of structurally related 6-substituted cyclohepta-l,4-dienes, which attract male gametes or induce their mass release (release factors). The most frequently occurring compounds include dictyotene (1), des-marestene (3), and lamoxirene (4). The latter is typical for the highly evolved order Laminariales, in which the pheromone induces spermatozoid release prior to attraction. The threshold concentration ofmale response towards the signal is typically found in the range of 10 nmol L~(-1) to 0.01 nmol L~(-1), depending upon algae species and pheromone function.