[77-77-0] · C4H6O2S · Divinyl Sulfone · (MW 118.17)
(bifunctional Michael acceptor that gives six-membered ring heterocycles with primary amines1 or analogous reagents;2 furnishes g-diketones in the reaction with aldehydes and a thiazolium salt (Stetter reaction);3 reasonably powerful dienophile4)
Physical Data: bp 233-234 °C; bp 90-92 °C/8mmHg; mp ca. -26 °C; d 1.177 g cm-3.
Form Supplied in: colorless liquid; commonly stabilized with hydroquinone; widely available.
Preparative Methods: by dehydration of bis-b-hydroxyethyl sulfone with phosphoric acid at 280 °C or by pyrolysis of bis-b-acetoxyethyl sulfone at 500 °C.5
Handling, Storage, and Precautions: toxic, corrosive liquid; vesicant and mild lachrymator; to be handled with care; use in a fume hood.
The two vinyl groups of the title reagent are activated towards nucleophilic additions, but they react also with electrophiles and radicals. Among the electrophilic additions is the reaction with aromatic diazonium salts (eq 1),6 while for supposed radical additions, the reaction of ketene alkyl trimethylsilyl acetals promoted by Titanium(IV) Chloride is representative (eq 2).7 The product of the latter reaction depends upon the substitution pattern at the a-carbon.
Other nucleophilic additions include reactions with primary amines (eq 3),1 phosphines (eq 4),2 and sodium peroxide (eq 5).8
Of synthetic relevance is the Stetter reaction,3 which provides a general route to polyfurans, polypyrroles, and polythiophenes,9 as represented in eq 6 for a terpyrrole.9b
Divinyl sulfone has been shown to react as both a dienophile and a dipolarophile. Examples of [4 + 2] cycloaddition10 include the reaction with cyclopentadiene (eq 7)4 and indole-2,3-quinodimethane (eq 8).10a In the former reaction the monoadduct can be isolated and reacted with another diene, while in the latter the first addition is followed by elimination of CO2 and CH2=CHSO2H, with direct formation of the aromatic carbazole. Dipolar cycloadditions are represented in eqs 9 and 10.11 In the latter example the 1,3-dipolar cycloaddition is preceded by a Michael addition.
Cycloaddition reactions of divinyl sulfone with benzyne (eq 11)12a and cobalt complexes of alkynes (eq 12)12b are also known.
Ottorino De Lucchi
Università di Venezia, Italy
Università di Sassari, Italy