Structure of 12-hydroxynorfluorocurarine, its hydrochloride, quaternary salts and a zwitterionic betaine

Abstract

The crystal structures of 12-hydroxynorfluorocurarine (vincanidine) isolated from the plant Vinca erecta, its hydrochloride monohydrate, quaternary salts — chloromethylate and iodomethylate, and the quaternary base (zwitterionic betaine) have been studied. The asymmetric centers of the molecules have the 3S, 7R, 15S configuration. In all cases, the carbonyl group is in a twisted orientation with respect to the N1H group and participates in the intramolecular H-bond with this group. In crystals, the 12-hydroxy group is involved in intermolecular interactions. The quaternary base of 12-hydroxynorfluorocurarine contains a zwitterionic form of the alkaloid due to deprotonation of the 12-hydroxyl group. The packing in the crystal structure of 12-hydroxynorfluorocurarine and the quaternary base contains voids (19.8 % and 21.8 % of the total volume of the crystal cell, respectively) of the channel type along the c crystallographic axis.