Preparation of acetal- and carbonyl-substituted allyl chlorides from alpha,beta-unsaturated acetals

The treatment of alpha,beta-unsaturated acetals 1-4 with Schlosser's reagen t LICKOR produces alkoxy-dienes 5-11 that can be readily transformed into a llyl chlorides 12-21 by reaction with NCS. The halides can be obtained with a protected or unprotected carbonyl function, depending an the reaction co nditions. The chlorination reaction proceeds by the electrophilic attack on the conjugate system that, depending on the substrate, affords both the 1, 4- and 1,2-addition derivative, or the pure 1,4-derivative. Upon treatment with LDA, allyl chloride 13 has been transformed into the chloro-functional ized alkoxy dienes Z-22 and E-22, or into the alkyne 23.