Efficient and stereoselective synthesis of yellow scale pheromone via alkyne haloboration, Zr-catalyzed asymmetric carboalumination of alkenes (ZACA reaction), and Pd-catalyzed tandem Negishi coupling

A Pd-catalyzed reaction of allylzincs with the 1-octyne bromoboration product gives the desired allyl-alkenyl coupling products in good yields except with H 2CCHCH 2ZnBr. This reaction is suitable for converting an alkyne bromoboration product 3 into 4 with no isomerization or beta-elimination. The Pd-catalyzed isoalkyl-alkenyl coupling of 4 with the isoalkylzinc reagent derived from 2 provides yellow scale pheromone ( 1) of >/=98% isomeric purity in 34% in six steps from TBDPS-protected homoallyl alcohol.