Synthesis of conjugated and unconjugated 1-alkadienols as candidates for insect attractants

(7E,9Z)-Et(CH:CH)2(CH2)nOAc [(7E,9Z)-I (n = 6)], the sex pheromone of Lobesia botrana, was prepd. (21.6%) from EtC≡CBr and MeCH:CH(CH2)6OR (R = tetrahydropyranyl) by sequential cross-coupling reaction [Pd(PPh3)4, MeONa], acetylation (AcOH, reflux, 6 h), and stereoselective redn. [(Me2CHCHMe)2BH, THF]. Similarly, (9Z,11E)-I (n = 8), a sex pheromone component of Spodoptera littoralis, was prepd. (30.2%) from (E)-EtCH:CHI and BrMgC≡C(CH2)8OR (R as before). (E)-CH2:CHCH:CH(CH2)8OAc, a sex pheromone component of Diparopsis castanea, was prepd. (54.3%) from H2C:CHBr and (Me2CHCHMe)2BCH:CH(CH2)8OR (R as before) by Pd(PPh3)4-catalyzed cross-coupling reaction followed by acetylation (Ac2O, AcOH, 80°)