Phenyl vinyl sulfones alkylation

The enamines derived from cyclic ketones give the normal alkylated products, although there is some evidence that unstable cycloadducts are initially formed (55b). Thus the enamine (28) derived from cyclohexanone and pyrrolidine on reaction with acrylonitrile, acrylate esters, or phenyl vinyl sulfone gave the 2-alkylated cyclohexanones (63) on hydrolysis of the intermediates (31,32,55,56). These additions are sensitive to the polarity of the solvent. Thus (28) in benzene or dioxane gave an 80% yield of the... 

Methyl vinyl sulfone forms 1,2-cycloaddition adducts with aldehydic enamines, both with and without 3 hydrogens (37). Simple alkylation was reported to take place when phenyl vinyl sulfone was allowed to react with cyclohexanone enamines (58,60), but it has recently been shown that phenyl vinyl sulfone also forms cyclobutane adducts (60a). 

Type III (no homodimerization) Acrylonitrile," protected 3° allylamines" Vinyl trialkoxysilanes, vinyl siloxanes 1,1-Disubstituted olefins, " non-bulky trisubstituted olefms, vinyl phosphonates, " vinyl phosphine oxides,phenyl vinyl sulfone, acrylonitrile, 4° allylic carbons (all alkyl substituents), protected 3° allylic alcohols, 7,Aolefm of 2-subst. 1.3- butadienes, 7,Aolefin of electronically deactivated 1.3- butadienes ... 

The Pandey group has developed a silver fluoride-promoted desily lation of tertiary bis(silyl)amines as an interesting alternative method to access azomethine ylides (Scheme 2.10).18 Notably, this method allows the generation of nonstabilized azomethine ylides under essentially neutral conditions. The starting materials are prepared by a three-step process, sometimes coupled into a single operation. For example, Boc-protected pyrrolidine 36 can be sequentially deprotonated and silylated twice in a one-pot reaction (Scheme 2.10). Removal of the Boc group and alkylation of the free amine leads to bis(silyl)amine 37. When this compound is treated with 2 equiv of silver fluoride in the presence of phenyl vinyl sulfone, rapid formation of products 39 as single stereoisomers results. 

Reductive addition to electron-deficient olefins can be also performed by using nontoxic (diacyloxyiodo)arenes (5, Scheme 3.4) [9]. In this case, the photocleavage of an iodo-oxygen bond forms an alkylcarboxyl radical that in turn decarboxylates to yield the desired alkyl radical. As an example, phenyl vinyl sulfones are easily alkylated (e.g., by the addition of adamantane) in good yields, provided that a good hydrogen donor such as 1,4-cyclohexadiene is present in solution. 

Lithiation of vinylic sulfones. Phenyl vinyl sulfones (1), prepared as indicated, react with methyllithium regiospecifically at — 95° at the a-vinyl position to give the lithium derivatives 2. As expected, 2 can be alkylated to give 3. The reaction of 2 with enolizable carbonyl compounds proceeds more satisfactorily by prior conversion to the vinylic Grignard reagent a. This sequence constitutes a route to disubstituted alkenes, since a sulfone group is reductively cleaved by sodium amalgam (7, 326). ... 

In these reactions, phenyl vinyl sulfones can be employed as 27t-components the cycloaddition occurs smoothly with a variety of dienes and the cycloadducts may be subsequently alkylated and desulfonated, providing a useful synthetic route to bicyclic compounds. For example, cyclopentadiene (146) reacts with phenyl vinyl sulfone (147) under forcing conditions to yield the adduct (148), which by alkylation and desulfonation affords bicydoheptane (149) (Scheme 60). 

The procedure for oxidation of the sulfide to the sulfone is based on that reported earlier by Bordwell and Pitt. The synthetic utility of phenyl vinyl sulfone and sulfoxide derives not only from their ability to serve as excellent Michael acceptors toward such reagents as enolate anions and organometallics, but also as moderately reactive dienophiles in Diels-Alder reactions. " The resulting adducts, in turn, can be chemically modified so that these electron-deficient olefins serve as useful synthons for acetylene,ethylene,terminal olefins,vinylsilanes, and ketene in [4 + 2] cycloadditions. Phenyl vinyl sulfone undergoes ready cycloaddition to Danishefsky s diene in the first step of a protocol for the regiospecific y-alkylation of 2-cyclohexenones. Furthermore, the ready lithiation of phenyl... 

The ort/to-alkylation of aromatic ketimines with functionalized olefins has been reported by Lim and co-workers. Among many olefin substrates bearing functional groups, acrylates and acrylamides showed good reactivity. The reaction could also be extended to other olefins, including phenyl vinyl sulfone and acrylonitrile, albeit with lower reactivity. The corresponding ketones were obtained after hydrolysis of the ketimines. 

Disubstituted alkenes, nonbulky trisubstituted alkenes, vinyl phosphonates, phenyl vinyl sulfone, tertiary aUylic carbons (all alkyl substituents), protected tertiary aUyUc alcohols nitroalkenes, protected trisubstituted aUyl alcohols... 

Phenyl vinyl sulfoxide can be polymerized and randomly oxidized to form sections of phenyl vinyl sulfone (VSO2) before elimination (vide supra) to control the conjugation length of the resulting PA (Scheme XVI) [74]. To a flask containing dry and distilled THF was added a few drops of alkyl lithium (1M solution) to remove any remaining impurities from the solvent. Next, more of the carbanion initiator (0.5 ml of a 1 M solution) was added, and the temperature was lowered to —78°C. The VSO monomer (5 ml) was then added, and the color of the solution turned to... 

The addition reaction with other alkyl bromides and xanthates to activated olefins such as phenyl vinyl sulfone and diethyl vinylphosphonate, with TPDS-AIBN, also gives the corresponding reductive addition products in moderate to good yields (40-84%). Unfortunately, reductive addition of chalcogenides to activated olefin with the TPDS-AIBN method does not work effectively due to the lower reactivity of chalcogenides toward the... 

Togo, H., Aoki, M., and Yokoyama, M., Reductive addition of alkyl radical to phenyl vinyl sulfone, Chem. Lett., 2169,1992. 

Vinylic sulfones undergo the same reaction especially when allylic, benzylic or t-alkylithium reagents are employed. One case of a vinyl sulfone deserves special mention - . When phenyl trans-3-bromopropenyl sulfone is treated with certain Grignard reagents it undergoes an alkylating cyclization ... 

These are good dienophiles. and aryl vinyl sulfones have found use as equivalents of ethylene and ketene through functional modifications of their adducts. However, as the base-induced elimination of a sulfinic acid to yield an olefin occurs only with difficulty, they are not direct precursors of acetylene equivalents, unless suitably modified as in ( )-l-phenyl-sulfonyl-2-trimethylsilyl ethylene (PhS02-CH=CH-TMS). In its cycloadducts the elimination to an alkene is smoothly realized by the fluoride ion. If an alkylation step is previously carried out on the adduct, the overall process realizes an indirect addition of a terminal acetylene, as in the examples given here [533]. 

Only a limited number of vinyl sulfones, e.g. phenyl ( )-2-phenylvinyl sulfone (14), undergo codimerization with MCR Homocyclodimerization of MCP is the most efficient side reaetion. Interestingly, yields and product distributions are solvent dependent. No reaction takes place with catalytic amounts of bis(t -cycloocta-l,5-diene)nickel(0)/triphenylphosphane. In this case the vinyl sulfones are strongly coordinated to the catalyst metal, thus preventing interaction with MCP. When the sulfones bear alkyl-substituted vinyl groups, isomerization to yield allyl sulfones usually proceeds faster than cycloaddition, at least in the case of palladium(O) catalysis. 

Thiazoles, vinyl-radical polymerization, 6, 278 Thiazole-5-sulfonic acid, 2-amino-synthesis, 6, 255-256 Thiazole-2-sulfonic acids reactions, 5, 104 6, 291 Thiazole-5-sulfonic acids synthesis, 6, 255 Thiazole-5-thione, 2-phenyl-tautomerism, 6, 249 Thiazolethiones reactivity, 6, 250 Thi azole-2-thiones reactions, 5, 102 tautomerism, 5, 367 Thiazolidine, 2-alkyl-occurrence, 6, 327 Thiazolidine, 2-arylimino-X-ray analysis, 6, 238 Thiazolidine, 4-imino-mesoionic didehydro derivative nomenclature, 1, 34 nomenclature, 1, 34... 

Polymers with phenyl pendant groups such as those present in polystyrene undergo all of the characteristic reactions of benzene, such as alkylation, halogenation, nitration, and sulfonation. Thus, oil-soluble polymers (e.g., poly(vinyl cyclohexylbenzene) used as viscosity improvers in lubricating oils are obtained by the Friedel-Crafts reaction of polyst3frene... 

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