Phenyl vinylsulfonate

Nevertheless, Michael acceptors such as phenyl vinylsulfone, ethyl cinna-mate, methyl acrylate, acrylonitrile and a, 3-unsaturated aldehydes failed to react in the reaction catalyzed by Yb(OTf)3 3H2O. 

Phenyl vinylsulfonate (16) is an effective dienophile and reacts with furan derivatives, which are known as inert dienes in the Diels-Alder reaction. The sulfonate 16 can be prepared in 85% yield by reaction of / -chlorosulfonyl chloride with phenol in the presence of sodium hydroxide and stored indefinitely at 0°C24. The cycloaddition reaction proceeds at room temperature to give predominantly endo adducts as illustrated in equation ll25. When the reaction was carried out at higher temperature, the yield of the endo adduct and the stereoselectivity decreased due to the retro-Diels-Alder reaction. 

A soln. of phenyl vinylsulfonate in dioxane added dropwise at room temp, to a stirred aq. soln. of cumyl hydroperoxide and NaOH, stirring continued until a test with Kl-glacial acetic acid shows the disappearance of the hydroperoxide phenyl / -cumylperoxyethanesulfonate. Y 65%. F. e., also with NaOD, s. H. Kropf et al., Tetrahedron 26, 1347 (1970). 

N,N-Dimethylcyclohexylamine added dropwise at 70-90° during ca. 2 hrs. to nitrocyclohexane and phenyl vinylsulfonate so that the mixture remains slightly basic, stirring continued 2-3 hrs. -> phenyl (1-nitrocyclohexyl) ethane-sulfonate. Y 78%. F.e. s. H. Distler, Ang. Gh. 77, 291 (1965). 

In the presence of bis-triphenylphosphine palladium-II-chloride as catalyst, the carbonylation of Diels-Alder products can be achieved even at 40 °C, e.g. with ethyl tetrahydrophthalate or diethyl bicyclo- (2.2.1)-heptene-(4)-dicarboxylate-l,2, which have a tendency to cleave into the starting materials. The catalyst combination (P(C2H5)3)2PdCl2 plus piperi-dine-triphenylphosphine palladium dichloride allows the carbonylation of phenyl-vinylsulfonate [406]. The relatively expensive but easily available catalyst [518] can be recycled many times. 

According to a recent Organic Syntheses procedure, fluoromethyl phenyl sul-fone, which can be prepared on a large scale [90] (Eq. 23), undergoes a number of useful reactions. A Wadsworth-Emmons-type procedure affords a-fluoro-vinylsulfones [91], which undergo tin-sulfur exchange under free radical conditions (Eq. 24). The products maybe protodestannylated [92],fluorinated [93],or coupled under palladium catalysis [94]. The difluoromethyl phenyl sulfone also shows some useful chemistry. 

The nucleophilic addition of lithiated allyl phenyl sulfone to nitrones at 0 °C afforded 4-(phenylsulfonyl)isoxazol-idines as major products. The process probably involves the isomerization of the allylsulfonyl moiety of the initially formed hydroxylamine anion to vinylsulfone which then undergoes intramolecular Michael addition. For example, the chiral nitrone 536 afforded isoxazolidine 537 with high diastereoselectivity (Equation 88) <2005T3335>. When the same reaction was carried out in the presence of hexamethylphosphoramide (HMPA) at —80°C, the anti-a-sulfonyl homoallyl hydroxylamine was obtained. 

Inhib. abbrev. DTT = dithioghreitol E64D = epoxysuccinyl-L-leucyl-amido-3-methyl-butane ethyl ester EDTA = ethylene-diamine-tetra-acetic acid EGTA = ethylen-glycol-tetra-acetic acid LHVS = morpholinurea-leucine-homophenyl-alanine-vinylsulfone-phenyl NEM = N-ethyl-maleimide PAI = plasminogen activator inhib. PMSF = phenil-methyl-sulfonil fluoride SBTl = soybean trypsin inhib. TIMP = tissue inhib. of metalloproteinases TPCK = tosyl-L-phenyl-alanyl-chloro-methane Al.so termed stephins. 

Vinylsulfones react homolytically with tributyltin hydride to give the corresponding vinylstannanes.22 24 An addition-elimination sequence seems most likely (equation 8-13), though an electron-transfer mechanism has also been suggested.22 Examples are given in equation 8-1422 and 8-15.23 A similar reaction has been demonstrated for vinyl phenyl sulfides.25... 

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