Methyl methacrylate, a cyclic olefin, and two alk-1-enes are efficiently converted into their corresponding epoxides by nt-chloroperbenzoic acid a t elevated temperatures in the presence of a small amount of a radical inhibitor, which prevents thermal decomposition of the peracid.:@-H20Hwas considered ; however, thermal decomposition of the peracid becomes a problem and the possibility that it might be suppressed in the presence of some radical inhibitor was investigated.?IN the course of an investigation directed towards a total synthesis of tetrodotoxin,l conversion of the olefin (I) into the epoxide (11) was required. This seemingly easy step turned out to be difficult because the double bond in the L b Ht) iiF ' olefin (I) has exceptionally poor reactivity towards peracids AC ( 1 ) such as m-chloroperbenzoic acid, peracetic acid, and performic acid. Epoxidation a t an elevated temperature Ac (II) t T. M. Luong and D. Lefort observed that the decomposition of perbenzoic acid in cyclohexane at 80 "C is suppressed in the presence However, these inhibitors are not efiective enough for the of 9-benzoquinone or hydroquinone (Bull. Soc. chim. France, 1962, 827). present purpose.$ We are indebted to Sumitomo Chemical Co., Ltd., for gifts of the radical inhibitors.3 Epoxidation of (I) with m-chloroperbenzoic acid (excess) a t 90 "C in the absence of the radical inhibitor gave a complex mixture.

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