Yoshitsugu Ikeda

A facile formation of cyclic selenuranes and a cyclic selenurane oxide in the reaction of 2-methylseleno- and 2-phenylselenobenzoic acids and their derivatives with t-butyl hydroperoxide

Abstract The reaction of 2-methylselenobenzoic acid with 1,1′-carbonyldiimidazole followed by addition of t-butyl hydroperoxide gave cyclic selenuranes 2a and 3a , suggesting the intramolecular insertion of the neighboring selenium atom into the OO bond of t-butyl 2-methylselenoperoxybenzoate. In the reaction of 2-phenylselenobenzoyl chloride with t-butyl hydroperoxide, cyclic selenurane 2b and the oxide 7 were obtained.

Chemical consequences of the intramolecular interaction between a sulphur atom and a methoxycarbonyl group in fluorene systems

The intramolecular interaction between a sulphur atom and a methoxycarbonyl group was found to affect their chemical reactivity. The rates of C–S bond cleavage in methyl 9,9-bis(ethylthio) fluorene-x-carboxylate, where x is 1, 2, or 3, with sodium ethanethiolate show that the rate is minimal, though comparable with the others, when x= 1, because of steric effects. In contrast, methyl 9-(ethylthio)fluorene-x-carboxylates, where x is 1, 2, or 3, exhibit the maximum rate when x= 1. The rates of ester exchange in the presence of toluene-p-sulphonic acid indicate that the reaction is accelerated by the presence of two ethylthio groups at the 9-position of methyl fluorene-1-carboxylate but no significant effect is detected if there is only one ethylthio group. The hydrolysis of the thioketal group in 9,9-bis(ethylthio)fluorene is also accelerated by the presence of a 1-methoxycarbonyl group. The implications of these results are discussed with the use of a model compound.