Stereoselective synthesis of activated cyclopropanes with an α-pyridinium acetamide bearing an 8-phenylmenthyl group as the chiral auxiliary

The reaction between an α-pyridinium acetamide bearing an 8-phenylmenthyl group as the chiral auxiliary and β-substituted methylidenemalononitriles gave rise to trans-cyclopropanes with diastereomeric ratios of up to 98:2. For most of the reactions, the absolute stereochemistry of the major product was found to be opposite of that of the major products of the reaction of the corresponding ester series, which also utilized the 8-phenylmenthyl group.