Desulfurization of epidithio-2,5-piperazinedione derivatives and their open chain analogs with triphenyl phosphine - Sato, T.; Hino, T. (Elsevier)
Desulfurization of epidithio-2,5-piperazinediones (6 and 7) by triphenylphosphine in THF gave dimeric compounds (8 and 15). In the presence of water or phenol the desulfurization gave 3-hydroxy (9) or 3-phenoxy-2,5-piperazinedione (10). Reaction of 6c with triphenylphosphine in ethyl vinyl ether yielded 2,5-diazabicyclo[2.2.2]octane-3,6-dione (11), indicating the presence of 1,4-dipole (B) as an intermediate of the desulfurization. Similar cycloaddition products (13 and 14) were obtained by the desulfurization of 6c in the presence of benzofuran, indole or skatole. Desulfurization of open chain disulfides (16, 21, 23 and 25) by triphenylphosphine gave reduced products (17, 22 and 26) and an isoxazole (18), but CC bond formation was not observed.
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Keywords: V