BASE INDUCED SKELETAL REARRANGEMENTS VIA SPIROCYCLIC IPSO INTERMEDIATES IN DIBENZODITHIOCINIUM SALTS

Article abstract of DOI:10.1016/S0040-4039(00)84768-1

Treatment of 6-methyl-12-oxo-5H,7H-dibenzo<1,5>-dithiocinium salt (1a) with methanolic KOH afforded the ring contracted product (2a), i. e., thiepin derivatives, trans-2a (44percent) and cis-2a (19percent).However, the corresponding deoxodithiocinium salt (1b) gave an unexpected isomer (2b) with the same thiepin skeleton.These are explained by tandem sigmatropy.