Nadh models-19

Abstract

N-(Cyclopropylmethylene)phenylamines ( 1a-c), cyclopropyl 2-pyridyl ketones ( 5-c) and ethyl cyclopropylmethlenepyruvate ( 14) have been subjected to reduction by l,4-dihydropyridines [3,5-diethoxycarbonyl-2,6-dimethyl-l,4-dihydropyridine ( 2) and/or 1-benzyl-1,4-dihydronicotinamide (7)]in the presence of magnesium ions, and by tin hydrides. The reactions with 1,4-dihydropyridines do not involve cleavage of the three-membered ring in the reduction step. The observed acyclic product from 2-pyridyl 2,2-dimethylcyclopropyl ketone ( 5b) is a consequence of ring cleavage prior to reduction of the carbonyl function. In contrast, reduction of 1a-c and 5-c by tin hydrides leads to products in which the cylopropane moiety has undergone ring-opening. These findings support a hydride transfer mechanism for reductions with NADH models.