intermediate carrying a carbonyl group at C6. Asymmetric syntheses of the bicyclic C6-C14 ethynyl building blocks were carried out starting fromachiral bicyclic C6-C12 ketones by using the chiral lithium amide method. In the course of these syntheses, a new method for the introduction of an ethynyl group at the alpha-position of the carbonyl group of a ketone with formation of the corresponding homopropargylic
furnished the allylicalcohol 62 which was converted to 4 in a standard fashion. It is at the stage of the α,β-unsaturated ester 60 where divergence into synthesis of 5 was made. Selective isomerization of 60 to the β,γ-unsaturated ester 66 of 97% ie in 91% yield was accomplished by deprotonation of 60 with 12 to enolate 65 and its subsequent regioselective protonation. By a similar reaction sequence the