SYNTHESIS AND REACTIONS OF A STABLE 2-SELENANAPHTHALENE, 1-CYANO-2-METHYL-2-SELENANAPHTHALENE

A stable 2-selenanaphthalene, l-cyano-2-methyl-2-selenanaphthalene (7), was prepared by deprotonation of l-cyano-2-methylisoselenochromenium salt (6) with triethylamine in ethanol. The selenanaphthalene 7 was air-sensitive and rearranged thermally in aprotic polar solvents to form 1-cyano-l-methylisoselenochromene (8) in good yield. Reaction of the selenanaphthalene 7 with dimethyl acetylenedicarboxylate in benzene afforded a benzocycloheptene derivative 15, whereas the same reaction in sulfolane afforded a naphthalene derivative 16 besides 15. Furthermore, the reaction in acetonitrile yielded a novel bisbenzocycloheptenyl derivative 17 together with 15. In contrast, the reaction of 7 with methyl propiolate gave a 2:1 adduct 23 in addition to the rearranged product 8 and isoselenochromene 3. Reactions with olefins bearing an electron-withdrawing group gave cyclopropane derivatives 27-32. © 1990, American Chemical Society. All rights reserved.