anti-Aldol reactions of chiral alcohol-substituted vinylogous urethanes and the synthesis of (−)-prelactone B

This paper describes a convenient and efficient method for synthesizing chiral alcohol-substituted vinylogous urethanes, in which the double bond has E configuration was determined by single crystal X-ray analysis. In addition, we investigated the anti-aldol reactions of these chiral vinylogous urethane anions. The use of (1S,2R,4R)-1-(hydroxydiphenylmethyl)-7,7-dimethylbicyclo[2,2,1]-heptan-2-ol as a chiral auxiliary, provided the best enantioselectivities, and the resulting vinylogous urethane lactone could be used for the synthesis of (−)-prelactone B. A plausible mechanism for the generation of major enantiomeric isomer was discussed.