[73476-18-3] · C11H18O2SSi · (2-Phenylsulfonylethyl)trimethylsilane · (MW 242.45)
(reagent for the synthesis of mono- and 1,1-disubstituted alkenes via sulfone metalation, alkylation, and fluoride-induced elimination1)
Physical Data: mp 52 °C.
Solubility: sol all common ethereal, halocarbon, and hydrocarbon solvents.
Form Supplied in: solid; commercially available.
Preparative Methods: (2-phenylsulfonylethyl)trimethylsilane (2) is prepared by radical addition of Thiophenol to Vinyltrimethylsilane to give (2-phenylthioethyl)trimethylsilane (1), which is then oxidized with Hydrogen Peroxide (eq 1).2,3
A sequence involving metalation, alkylation, and fluoride-induced elimination of benzenesulfinate allows the conversion of (2) to a terminal alkene. An analogous sequence involving a double alkylation of (2) provides a 1,1-disubstituted alkene (eq 2).4,5 The lithio derivative of (2) has also been used to prepare cyclopropylidene derivatives,6 homoallylic alcohols,7 and allyl silanes via the Julia alkenation.3
Although the fluoride-induced elimination is a reliable and efficient method for synthesizing alkenes, the requisite silyl sulfone precursors are often better prepared by methods which avoid the use of (2). For example, eq 3 illustrates an alternative synthesis of 2,2-dialkyl-2-(phenylsulfonylethyl)trimethylsilanes involving alkylation of a lithio sulfone with (Iodomethyl)trimethylsilane.8,9
2-(Phenylsulfonylvinyl)trimethylsilane (3) is a useful acetylene equivalent for use in Diels-Alder reactions (eq 4).10,11
Phenylsulfonylethylene derivatives undergo conjugate addition reactions. Thus (3) reacts with unsaturated Grignard reagents and organocuprates,12 while the substituted sulfone (5) undergoes conjugate addition by the enolate derivative (4) to give a bicyclomycin intermediate (eq 5).13
Georges Hareau & Philip Kocienski
Southampton University, UK