Non-destructive 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 converted into enantiomerically pure ketones 5, 13, and 14, respectively, via a two-step procedure involving a known mercaptolysis reaction followed by an [Fe(acac)(3)]-mediated coupling of the resulting S-benzyl thioesters with Grignard reagents. Futhermore, enantiomerically pure aldehydes 23 can be obtained from alpha-substituted N-acylbornane-10,2-sultams 6 via a one-step reduction with (i-Bu)(2)AlH. No epimerization at the alpha-chiral center is observed during the cleavage reaction whereby the chiral auxiliary, bornane-10,2-sultam 1 or ent-1, was recovered. By using this methodology, several natural products or precursors thereof can be prepared.