1-Thioniabicyclo [4.4.0] decane bromide (I) derived from 1, 9-diphenoxy-5-mercaptononane was found to be composed of isomers, Ia and Ib, in the ratio of 2 : 3, each of which was purified by column chromatography on silica gel. On heating at 260-270°, Ia was partially isomerized to the equilibrium mixture of Ia and Ib in 3 : 2 ratio, as did Ib. The structures of Ia and Ib were established as cis and trans isomers, respectively, on the basis of the carbon-13 neuclear magnetic resonance spectral studies. The reaction of Ia and Ib with sodium amalgam gave 2-butylthiane and thiecane. Heating of Ia and Ib with aqueous potassium hydroxide gave 2-(3'-butenyl) thiane, trans-3, 4, 7, 8, 9, 10-hexahydro-2H-thiecine and 2-(4'-hydroxybutyl) thiane.
