Synthesis, structure, and oxidation of 3,4‐dihydro‐1,2,5‐benzotrithiepins

Abstract

Stable benzene-fused polysulfide compounds, 3,4dihydro-l,2,5-benzotrithiepins (la-c), have been prepared, and the structure of la has been determined by X-ray crystallographic analysis. While the electrophilic oxidation of compounds 1 with m-chloroperbenzoic acid gave the cowesponding 3,4-dihydro-l,2,5benzotrithiepin 5-oxides (2) in moderate yields, the oxidation of 1 with N-bromosuccinimide afforded a mixture of 5-oxides 2, unexpected, inseparable 3,4dihydro-l,2,5benzotrithiepin 2,2-dioxides (3), and 3,4dihydro-l,2,5-benzotrithiepin 1 ,I -dioxides (4). Semiempirical PM3 calculations were carried out, and the computed HOMO of la suggested a significant favoring of ebctrophilic reactions at the sulfur atom at the 5-position. The treatment of 5-oxides 2 with acetyl bromide or oxalyl dibromide as halogenating reagents gave 2,2-dioxides 3 and 1,l-dioxides 4, suggesting that an intramolecular halogen transfer from the 5-position (sulfide moiety) to the 1-and 2-positions (disulfide moiety) took place in the reactions.C 1995 VCH Publishers, Inc.

On the Origin of Cytotoxicity of the Natural Product Varacin. A Novel Example of a Pentathiepin Reaction That Provides Evidence for a Triatomic Sulfur Intermediate

“…Little is known of the intermediates involved in the biochemistry of pentathiepins. Pentathiepins have been used as reagents in organic synthesis, − but it has not been possible to detect the reactive species spectroscopically. Even elucidating aspects of the reaction mechanism by product identification has presented problems.…”