“…In order to elucidate the mechanism of the selectivity in oxidation of a pair of thiols, HSCH 2-(CONH)2C6H4N(CH3) 2 and HSCH2CH2(NHCO)2-R (R = alkyl), we have determined the crystal structures of the former compound (Uchida, Ohashi, Sasada, Kaneko & Endo, 1983) and its model compound C6HsCHE(CONH)EC6H4N(CH3) 2 (Ohashi, Uchida, Sasada, Kinoshita & Endo, 1984). Further studies on the complex formation were carried out using several pairs of acylurea derivatives, R I--(CONH)EC6H4N-(CH3) 2 and RE-(NHCO)EC6H4NO 2, where R 1 and R E are non-polar groups (Endo, Miyazawa, Endo, Uchida, Ohashi & Sasada, 1982;Endo, Miyazawa, Endo, Kato, Uchida, Ohashi '& Sasada, 1983). The p-nitrophenyl group was used since it has similar shape but opposite electronic character to the pdimethylaminophenyl group and the selectivity for C6H4NO 2 in the oxidation is approximately the same as that for C6H4N(CH3) 2.…”