A NOVEL CARBON CARBON BOND-FORMING REACTION OF TRIFLATES WITH COPPER(I)-CATALYZED GRIGNARD-REAGENTS - A NEW CONCISE AND ENANTIOSPECIFIC SYNTHESIS OF (+)-EXO-BREVICOMIN, (5R,6S)-(-)-6-ACETOXY-5-HEXADECANOLIDE, AND L-FACTOR

We describe here a full account of a highly concise and enantiospecific synthesis of (+)-exo-brevicomin (7), (5R,6S)-(-)-6-acetoxy-5-hexadecanolide (11), and L-factor (16) originating from d- or L-tartrates as chiral sources. The synthesis employs an efficient carbon—carbon bond-forming reaction of triflates with copper(I)-catalyzed Grignard reagents and, as a consequence, tosyl—triflate derivatives 6 and 15 were found to be a versatile intermediate. This methodology completed the synthetic scheme involving a five-step sequence from 1 to 7, a 10-step sequence from 2 to 11, and a seven-step sequence from 12 to 16. The results present a new rapid means to derive optically active natural products from readily available chiral building blocks. © 1990, American Chemical Society. All rights reserved.