Novel formation of 4-methylthiopyrene in a Hofmann elimination reaction directed toward the synthesis of 17,19-dioxa[2.2.3](1,2,3)cyclophanediene

Abstract

The synthesis of 17,19-dioxa[2.2.3](1,2,3)cyclophanediene was attempted via a Stevens rearrangement–Hofmann elimination sequence on 19,21-dioxa-2,11-dithia[3.3.3](1,2,3)cyclophane. Pyrene and 4-methylthiopyrene were, however, the isolated products. The structure of the latter was fully characterized by UV, MS, 1D and 2D 1H NMR spectra. Formation of 4-methylthiopyrene was expected to involve a novel base-induced ring cyclization resulting in elimination of methanoate anion from the methylenedioxy bridge followed by a novel 1,4-hydride shift resulting in the elimination of methane.