NONDESTRUCTIVE REMOVAL OF THE BORNANESULTAM AUXILIARY IN ALPHA-SUBSTITUTED N-ACYLBORNANE-10,2-SULTAMS UNDER MILD CONDITIONS - AN EFFICIENT SYNTHESIS OF ENANTIOMERICALLY PURE KETONES AND ALDEHYDES

alpha-Substituted N-acylbornane-10,2-sultams 6, 9, and 10 can be conve rted into enantiomerically pure ketones 5, 13, and 14, respectively, v ia a two-step procedure involving a known mercaptolysis reaction follo wed by an [Fe(acac)(3)]-mediated coupling of the resulting S-benzyl th ioesters with Grignard reagents. Futhermore, enantiomerically pure ald ehydes 23 can be obtained from alpha-substituted N-acylbornane-10,2-su ltams 6 via a one-step reduction with (i-Bu)(2)AlH. No epimerization a t the alpha-chiral center is observed during the cleavage reaction whe reby the chiral auxiliary, bornane-10,2-sultam 1 or ent-1, was recover ed. By using this methodology, several natural products or precursors thereof can be prepared.