Another mode of heterocyclization of an enantiopure C2-symmetric bis-epoxide leading to the symmetric dialkyl sulfide

Reexamination of heterocyclization of an enantiopure C2-symmetric bis-epoxide (7) with sodium sulfide is described. In addition to the reported processes leading to thiane (4a) and thiepane (6), another mode of cyclization was found to occur to a considerable extent, affording a symmetric dialkyl sulfide (5), and the structure of the main product reported (4a) has been revised. Conditions for the chemoselective formation of 6 were established, and effective transformation of 6 into 4 was accomplished by the modification of the processes.

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