Enantioselective Reduction of meso-Cyclic-1,2-dicarboxylic Anhydrides and 1,2-Dicarboximides: Asymmetric Synthesis of Bicyclic Lactones and Hydroxylactams.
Enantioselective Reduction of meso-Cyclic-1,2-dicarboxylic Anhydrides and 1,2-Dicarboximides: Asymmetric Synthesis of Bicyclic Lactones and Hydroxylactams.
Bicyclic 5-hydroxy-2-pyrrolidinones (2a - f) were synthesized with high enantioselectivity by the reduction of meso underbar-cyclic- 1,2-dicarboximides (1a - f) with lithium aluminum hydride (LiAlH4)- methanol (MeOH)- 1,1'-bi-2-naphthol complex (BINAL-H). Treatment of 2a - f with triethylsilane (Et3SiH) and trifluoroacetic acid(CF3CO2H) gave optically active 2-pyrrolidinones (3a - f) in quantitative yields. For the absolute configuration correlation, 2a - d were converted into known lactones (4a - d).