Sulfene is an extremely reactive

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one ele ...

with the formula H₂C=SO₂. It is the simplest member of the sulfenes, the group of compounds which are ''S'',''S''-dioxides of

thioaldehydes In organic chemistry, a thial or thioaldehyde is a functional group which is similar to an aldehyde, , in which a sulfur (S) atom replaces the oxygen (O) atom of the aldehyde (R represents an alkyl or aryl group). Thioaldehydes are even m ...

and

thioketone In organic chemistry, thioketones (; also known as thiones or thiocarbonyls) are organosulfur compounds related to conventional ketones in which the oxygen has been replaced by a sulfur. Instead of a structure of , thioketones have the structure ...

s, and have the general formula R₂C=SO₂.

Preparation

The first general method for preparation of sulfene as an intermediate, reported simultaneously in 1962 by Gilbert Stork and by Günther Optiz, involved removal of

hydrogen chloride The compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colourless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hydrogen chloride g ...

from methanesulfonyl chloride using

triethylamine Triethylamine is the chemical compound with the formula N(CH2CH3)3, commonly abbreviated Et3N. It is also abbreviated TEA, yet this abbreviation must be used carefully to avoid confusion with triethanolamine or tetraethylammonium, for which TEA ...

in the presence of an

enamine An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates. : The word "enamine" is derived from the affix ''en''-, used as the suffix of alkene, and the ...

as trapping agent. The formation of a thietane 1,1-dioxide derivative was taken as evidence for the intermediacy of sulfene. Because of the highly

electrophilic In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that car ...

character of sulfene, the use of amines presents difficulties, since they can intercept the sulfene to form

adduct An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...

s. A simple alternative which avoids the use of amines involves desilylation of trimethylsilylmethanesulfonyl chloride with cesium fluoride in the presence of trapping agents. : (CH₃)₃SiCH₂SO₂Cl + CsF → H₂=SO₂+ (CH₃)₃SiF + CsCl Alternatively, sulfenes can be stabilized by installing amido substituents on the alkylidene substituent. The extreme case is

thiourea dioxide Thiourea dioxide or thiox is an organosulfur compound that is used in the textile industry. It functions as a reducing agent. It is a white solid, and exhibits tautomerism. Structure The structure of thiourea dioxide depends on its environment. C ...

, which features planar amido groups. : SURDOX

Reactions

Sulfenes react with enamines, ynamines, and 1,3-cyclopentadienes to give thietanes,

thiete Thiete is a heterocyclic compound containing an unsaturated four-membered ring with three carbon atoms and one sulfur atom. It is more commonly encountered not on its own, but in anellated derivatives, several of which have been synthesized. Th ...

s and Diels-Alder adducts, respectively. In the presence of a

chiral Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from i ...

tertiary amine complex, several sulfenes could be trapped with trichloroacetaldehyde (

chloral Chloral, also known as trichloroacetaldehyde or trichloroethanal, is the organic compound with the formula Cl3CCHO. This aldehyde is a colourless oily liquid that is soluble in a wide range of solvents. It reacts with water to form chloral hydrate ...

) in a catalytic asymmetric synthesis of β-

sulfone In organic chemistry, a sulfone is a organosulfur compound containing a sulfonyl () functional group attached to two carbon atoms. The central hexavalent sulfur atom is double-bonded to each of two oxygen atoms and has a single bond to each of ...

s (four-membered ring sulfonate esters). Sulfene can also undergo insertion into metal–hydrogen bonds.

References

{{reflist Organosulfur compounds

Preparation

Reactions

See also

References