Diastereoselective synthesis of optically active rotaxane amine N-oxides via through-space chirality transfer

Selective synthesis of optically active rotaxane amine N-oxides was achieved with high diastereoselectivity via the effective through-space chirality transfer. Oxidation of tert-amine moiety on axle component of rotaxane with an optically active wheel component having (R)-binaphthyl group was carried out. The oxidation of several rotaxanes with dimethyldioxirane was conducted in dichloromethane at -78 degrees C to give the corresponding amine N-oxides with high diastereoselectivity up to 95%, indicating the conversion via the effective through-space chirality transfer. Higher diastereoselectivity was observed with the rotaxane possessing the rigid skeleton and the N-benzyl substituent. The optimized structures suggested the stereochemistry of the nitrogen center of (R)-configuration. (C) 2016 Elsevier Ltd. All rights reserved.