An Unorthodox Pathway to the 1,2‐Dithiin System

Abstract

Tetracyanoethylene combines with two molecules of thiobenzophenone in refluxing benzene to give the tetrasubstituted 1,2-dithiin 8 ( 2 1~2 9 % ) besides the corresponding thiophene derivative 9 (40-52%). The X-ray analysis of the ruby-red 8 reveals a half-chair conformation with a torsion angle of 58.9" at the disulfide bond. The thermal desulfurization 8 -+ 9 (benzonitrile, 100°C) proceeds with flI2 = 26.7 h, whereas the sulfur loss induced by triethyl phosphite is a billion times faster. The mechanisms of the formation of 8 and its sulfur extrusion are discussed in the light of recent literature.

Unusual formation of a thiacyclopent‐2‐ene by the reaction of 4,4′‐dimethoxythiobenzophenone with tetracyanoethylene

“…This result is quite different from that reported by Huisgen et al [3,6]. They have reported that the reaction of 1a with TCNE in refluxing chloroform afforded only 2a in 78% yield, and the reaction of thiobenzophenone (1b) with TCNE in refluxing benzene afforded 2b (Ar‫ס‬Ph) and 3b (Ar‫ס‬Ph) in 52% and 29% yields, respectively.…”

“…Another molecule of 4,4Ј-dimethoxythiobenzophenone (1a) reacted with 6 via a [4 ‫ם‬ 2] manner to afford the sixmembered cyclic disulfide (7), which finally extruded sulfur to give 5a. The formation mechanism of 2 had already been suggested by Huisgen et al [6]. The thioamide 6 was further attacked by another molecule of thiobenzophenone (1a) to yield maleonitrile and/or fumaronitrile derivatives (8).…”

“…The four-membered intermediate is easily converted into the ring-opened thioamide (6). Another molecule of 4,4Ј-dimethoxythiobenzophenone (1a) reacted with 6 via a [4 ‫ם‬ 2] manner to afford the sixmembered cyclic disulfide (7), which finally extruded sulfur to give 5a.…”

Generation, Reactivity and Uses of Sulfines in Organic Synthesis

“…[110] Cycloadducts of sulfines with aliphatic thiones are more stable, this is shown by work carried out by Huisgen who isolated spiroadamantine-derived cycloadduct 94, and bis-spiroadamantane-derived cycloadduct 95 in high yields from cycloaddition reactions ( Figure 5). [111] Eur. J. Org.…”

Episulfidation of trans‐Cyclooctene with an 1,2,4‐Oxadithiolane

“…The synthesis of a series of differently substituted 1,2,4oxadithiolanes have been reported a few years ago in [2ϩ3] cycloadditions of aliphatic thioketones with dialkyl or diaryl sulfines; some of them were shown to convert into 1,2,4-trithiolanes on thermal decomposition. [4] While the both derived from the 1,2,4-oxadithiolane I, are proposed as elusive episulfidating agents.…”