Unusual transformation of the 1-bromotricyclo[4.1.0.02,7]-heptane adduct with methanesulfonyl thiocyanate in the presence of DBU

Abstract

SHORT COMMUNICATIONSWe recently reported [1] on the reactions of 1-bromotricyclo[4.1.0.0 2,7 ]heptane with benzene-and methanesulfonyl thiocyanate, which afforded trisubstituted norpinanes 1a and 1b differing by the substituent in the sulfonyl group. In this work we studied the behavior of norpinane 1a in the presence of bases. In particular, the reaction of 1a with 2 equiv of DBU in methylene chloride at 20°C gave thioketone 2 which readily underwent alkaline hydrolysis to norpinanone 3. Under the same conditions, norpinane 1b gave rise to a mixture of norpinanone 4 with endo orientation of the sulfonyl group (unlike ketone 3) and two unexpected products, trisubstituted norpinane 5 and disulfane 6, at a ratio of 3 : 2 : 1 (according to the 1 H NMR data; Scheme 1).Pure compounds 4-6 were isolated by flash chromatography on silica gel. The structure of 4 was confirmed by IR and 1 H and 13 C NMR spectra with account taken of the data for known benzenesulfonyl analog [1]. The configuration of C 7 was assigned on