Synthesis of Alkenyl‐Substituted Allenecarboxylates

The Wittig olefination of decanoyl chloride by using the phosphonium salt 1 in the presence of two equivalents of Et 3 N represents a one‐step synthesis of the racemic form of the naturally occurring pheromone (–)‐ 2 which contains an alkenyl‐substituted allenic moiety (ef. Scheme 1) . It is also shown, that unsaturated acyl chlorides which contain at least one γ‐H‐atom undergo the Wittig reaction with an appropriate phosphorane yielding γ‐alkenyl‐substituted α‐allenic esters and α‐allenic γ‐lactones, respectively (ef. Schemes 2 and 3) .