Synthesis of 3, 6-Diethoxycarbonyl-3, 6-epidithia-1, 4-dimethyl-2, 5-piperazinedione and Related Compounds. Formation of C-S Bond by the Reaction of Carbanion and Sulfur Monochloride

Abstract

Reaction of 3, 6-diethoxycarbonyl-1, 4-dimethyl-2, 5-piperazinedione (15), prepared by heating of diethyl methylaminomalonate (14), with NaH in dioxane and followed treatment with S₂Cl₂ gave 3, 6-epidithio- and 3, 6-epitetrathio-3, 6-diethoxycarbonyl-1, 4-dimethyl-2, 5-piperazinediones (16b and 16d), which have the skeletone (1) observed in fungal metabolites such as sporidesmin. The reduction of 16 with NaBH₄ in methanol gave the dethio derivative (15) in good yield. The reaction of 16d with triphenylphosphine in tetrahydrofurane gave 16c and 16b. The reaction of diethyl malonate derivatives (23a, b, and c) with NaH and S₂Cl₂ in dioxane gave the corresponding disulfides or trisulfides (24a, b, and c). Some reactions of proline anhydride (5) and sarcosine anhydride (7) with S₂Cl₂ or sulfur were examined.