Synthesis and Nuclear Magnetic Resonance Study of 2-Thiazolines

Article abstract of DOI:10.1021/je00037a038

A series of 5,5-dimethyl-2-thiazoline-4-carboxylates with a phenyl or methyl group at the 2-position of the ring were prepared from the corresponding methyl or ethyl ester of penicillamine and either methyl benzimidate or ethyl acetimidate.The free acid was obtained by the reaction of penicillamine with benzonitrile to produce 5,5-dimethyl-2-phenyl-2-thiazoline-4-carboxylic acid.Corresponding thiazolines were prepared from cysteine in the same manner.The nuclear magnetic resonance spectra of both series exhibit coupling of the methyl group at the 2-position with the hydrogen at the 4-position.The groups at the 5-position are nonequivalent and in the case of the cysteine series give rise to an ABX system.Further analysis confirms a concentration dependence for this splitting pattern.