Synthesis of (Z)-14-heptadecen-4-olide and (Z)-11-pentadecen-4-olide, sex pheromone analogues of Ostrinia nubilalis and cydia molesta

The key step in the preparation of racemic ( Z )-14-heptadecen-4-olide ( VIa ) and (Z)-11-pentadecen-4-olide (VIb), sex pheromone analogues of Ostrinia nubilalis and Cydia molesta , was efficient cross-coupling reaction of 3-methoxycarbonylpropanoyl chloride with corresponding ( Z )-alkenylmagnesium bromides. The methyl 4-oxo-( Z )-14-heptadecenoate ( Va ) and methyl 4-oxo-( Z )-11-pentadecenoate ( Vb ) prepared in this way were converted by one-pot reaction using sodium borohydride in an ethanolic solution to the required ( Z )-alken-4-olides ( VIa , VIb ).