Thiirene dioxides. Synthesis, characterization, and reactivity

Abstract

The synthesis of 2,3-diphenylthiirene 1,1-dioxide (12) by a modified Ramberg-Bácklund reaction is described, a,a '-Dibromodibenzyl sulfone (11) was obtained by (a) bromination of dibenzyl sulfide followed by oxidation or (b) brominative decarboxylation of a,a '-diphenylsulfodiacetic acid (13). Without separation of the mixture of diastereomeric dibromides, treatment with triethylamine in refluxing methylene dichloride gave 12. The structure of 12 was established by reduction to the corresponding dihydro derivative, m-2,3-diphenylthiirane 1,1dioxide (21), by means of aluminum amalgam in wet ether. Reaction of 12 with phenyldiazomethane gave adiazobenzyl 1,2-diphenylvinyl sulfone (19). Three alkyl-substituted thiirene dioxides were obtained by a general method which involves generation of a sulfene from an -bromoalkanesulfonyl chloride and triethylamine in the presence of a diazoalkane. Interaction of the sulfene and diazo compound leads to a bromoepisulfone which is dehydrobrominated by means of triethylamine or a stronger base. The method was applied to the synthesis of the monomethyl (32), dimethyl (38), and 2-methy 1-3-phenyl (39) derivatives. The most unusual property of the thiirene dioxides is their marked stability relative to their saturated analogs, a fact which is suggestive of special conjugative effects.

[Sulfonylbis(bromomethylene)]dibenzene

“…Details of the synthesis of the title compound are not given in the Bordwell papers, but details of two methods of preparing the compound are given in Carpino et al (1971).…”

1,3‐Dipolar Cycloreversions

“…The two dimers undergo 1,3-dipolar cycloreversion, as proved by their thermochromism and by trapping (128) with dimethyl acetylenedicarboxylate119'" The cycloadduct (131) obtained by heating a trans-stilbene oxide derivative with diethyl mesoxalate undergoes 1,3-dipolar cycloreversion to the carbonyl ylide (132) which adds afresh to diethyl mesoxalate to give (133)f1921.…”

Sulfur-Containing Carbanions

“…2-66) (Carpino et al, 1971). A novel "bishomoconjugative" analog of the Ramberg-Bäcklund reaction has been reported (Eq.…”