Synthesis of Alkenyl-Substituted Allenecarboxylates

The Wittig olefination of decanoyl chloride by using the phosphonium salt 1 in the presence of two equivalents of Et₃N 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).