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Stereoselective synthesis of gamma-lactone fused cyclopentanoids

2012-10-15
Gumus, Aysegul
Tanyeli, Cihangir
The stereoselective synthesis of gamma-lactone fused cyclopentanoids applying chemoenzymatic methods is described. rac-2-Hydroxymethyl-1,4,5,6-tetrachloro-7,7-dimethoxybicyclo[2.2.1]hept-5-ene and rac-2-hydroxymethyl-1,4,5,6,7,7-hexachlorobicyclo[2.2.1]hept-5-ene were successfully resolved by Candida rugosa lipase (CRL), to afford enantiomerically enriched products with an ee of 94 and 97%, respectively. The enantiomerically enriched acetates were then subjected to ruthenium and/or cerium catalyzed oxidation to afford alpha-diketones and subsequent alkaline H2O2 mediated oxidative cleavage reaction of alpha-diketones, followed by CH2N2 esterification, gave enantiomerically enriched gamma-lactone fused cyclopentanoids with known absolute configurations. (C) 2012 Elsevier Ltd. All rights reserved.