Thioesters, synthesis from alkenes

Heterocycles can be prepared from selenium-induced cyclizations of urethanes, thioesters and alkenes. These cyclizations are seen infrequently, but have much potential in heterocyclic synthesis. The aniline (37) was treated with benzeneselenenyl chloride and silica gel (to facilitate the ring closure) to produce the hexahydrocarbazole (38) in good yield (equation 30). Sulto heterocycles are prepared similarly to nitrogen heterocycles. ... 

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