Structure and Synthesis of (±)‐Caudoxirene, a New Spermatozoid‐Releasing and ‐Attracting Pheromone from the Marine Brown Alga <i>Perithalia caudata</i> (Phaeophyceae, Sporochnales). Part V

Abstract

Abstract Cis‐ 3 ‐(trans‐ 1,2‐Epoxybut‐3‐enyl)‐4‐vinylcyclopentene ((±)‐ 4 , caudoxirene) is a new gamete‐releasing and gamete‐attracting pheromone from the marine brown alga Perithalia caudata (Sporochnales). The key step of its synthesis is the diastereoselective alkylation of the aldehyde 8 with the [(phenylthio)allyl]titanium reagent 9 to yield the erythro ‐β‐hydroxy sulfide 10 which affords 4 on sequential treatment with Me 3 O·BF 4 and aq. NaOH. The lowest effective concentration of (±)‐ 4 for gamete‐release is found at 1.4 × 10 −11 mol/l seawater.