Non‐destructive Removal of the Bornanesultam Auxiliary in α‐Substituted N‐Acylbornane‐10,2‐sultanis under Mild Conditions: An efficient synthesis of enantiomerically pure ketones and aldehydes

Abstract α‐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. Furthermore, enantiomerically pure aldehydes 23 can be obtained from α‐substituted N ‐acylbornane‐10,2‐sultams 6 via a one‐step reduction with (i‐Bu) 2 AIH. No epimerization at the α‐chiral center is observed during the cleavage reaction whereby the chiral auxiliary, bornane‐10,2‐sultam 1 or ent ‐ l , was recovered. By using this methodology, several natural products or precursors thereof can be prepared.