Allyl-phenyl-sulfone

Vinyl sulfones such as 262 are smoothly converted to a,) -unsaturated nitriles such as 263 on treatment with KCN in the presence of dicyclohexyl-18-crown-6 in refluxing t-butyl alcohol (equation 155)148. The reaction conditions are compatible with base-labile functionalities such as a methoxycarbonyl group (equation 156)148. This method can be used in the preparation of the sesquiterpene aldehyde nuciferal from allyl phenyl sulfones. 

The oxidative dimerization of the anion of methyl phenyl sulfone (from a Grignard reagent) in ethereal solution in the presence of cupric chloride in 5% yield has been reported47. Despite the reported48 poor stability of the a-sulfonyl C-centered radicals, Julia and coworkers49 provoked the dimerization (in 13 to 56% yields) of the lithiated carbanion of alkyl phenyl sulfones using cupric salts as oxidants. The best results are obtained with cupric triflates in THF-isobutyronitrile medium (56% yield for R = H). For allyl phenyl sulfones the coupling in the 3-3 mode is predominant. 

In one example of this type of cyclization aminoalcohol, 288, which was obtained by conjugate addition of racemic 2-(2-hydroxyethyl)piperidine to allyl phenyl sulfone, was converted into the corresponding chloride and cyclized in the presence of LDA to give 289 as a single diastereomer (Scheme 63) <2003JOC9389>. In a related approach, the primary alcohol group was activated for a similar cyclization by transformation into a mesylate <20010L2957>. 

Alternatively, the ambident oi-hetero substituted allyl anions have been utilized as homoenolate equivalents. For example, in the presence of HMPA, allyl phenyl sulfides (251),192 allyl phenyl sulfones (252)192b c and allyl phenyl selenides (253)192d e add to a,(3-enones in a l,4(0)-mode, while allyl phenyl sulfoxides (254) and allyl phosphine oxides (255) afford 1 A j-addition exclusively, irrespective of solvent used.193 Hua has shown that additions of either chiral sulfoxide (254 R1 = R2 = R3 = R4 = H, R5 = p-tolyl) or allyl oxazaphospholidine oxide (256) occur with excellent enantioselectivity (>95% ee).194 Similarly, Ahlbrecht reports that the a-azaallyl (257) adds exclusively in a 1 A j-mode to acceptor (59) to afford 1,5-diketones (Scheme 86).195... 

The nucleophilic addition of lithiated allyl phenyl sulfone to nitrones has proceeded exclusively a to the phenylsulfonyl group affording anti adducts in high yield.47 At (g 0 °C isoxazolidines have been obtained with complete al -trans selectivity. 

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. 

The butyllithium-generated anion of an allylic sulfone was reported to add to conjugate enones, but different regioselectivity was observed for 2-cyclohexenone (1,4-y) and 3-penten-2-one (1,4-a), as shown in equation (31). Clean 1,4-a additions to both acyclic and cyclic enones can be realized when the lithio carbanions are allowed to react in the presence of HMPA (2 mol equiv.) at -78 C. Under these conditions, allyl phenyl sulfone reacts with 2-cyclohexenone. 2-methyl-2-cyclopentenone and 3-methyl-2-cyclohexenone, giving the corresponding 1,4-a adducts as a 75 25 mixture of two dia-stereoisomers. In the reaction of allylic phenyl sulfone with an acyclic enone, 4-methyl-3-penten-2-one,... 

Under similar conditions, no cyclopropanation of allyl phenyl sulfones takes place, but rather [2,3] rearrangement of a primarily formed sulfur ylide. With but-2-enenitrile, oxazole formation rather than cyclopropanation occurs. " ... 

The bis-alkylation of the dilithio derivative of allyl phenyl sulfone with ( )- ,4-dichlorobut-2-ene (7) affords the cw-cyclopropane 8 which rearranges in refluxing xylenes into the cyclohepta-1,4-diene system 9 in 65% overall yield. 

Allylic sulfonyl carbanions react with electrophiles such as alkyl halides and aldehydes at the a-position. Although relatively strong bases like Bu"Li and LDA are usually used for deprotonation of allylic sulfur compounds, including sulfones, a catalytic two-phase system that consists of a concentrated aqueous NaOH solution and a quaternary ammonium salt can be used to generate allylic sulfonyl carbanions. 1,1-Dilithiated allyl phenyl sulfone (equation 20) reacts with excess benzaldehyde to afford the 1,3-( )-diadduct, while l,ort/io-dilithiated allyl phenyl sulfone gives the l,ort/io-diadduct predominantly. Other examples of sulfur-substituted allylic anions are summarized in Table 1. 

In the simplest application of this concept, Chatgilialoglu and Curran carried out allylation reactions with allyl phenyl sulfones in the presence of tris(trimethylsilyl)-silane [58]. These reactions are analogous to the tin-mediated reactions previously discussed however, tris(trimethylsilyl)silane is used instead of tributyltin hydride or hexabutylditin for propagating the radical chain. The yields in these reactions ranged from moderate to good. 

C-Alkylations. Allylic phenyl sulfones undergo alkylation very readily when the anions are generated in the presence of aqueous NaOH and tetrabutylammonium bromide With dibromoalkanes, cyclic products are obtained. 2,2-Dibromo-l-phenylcyclopropane and a-substituted phenylacetonitriles react to give cyclopropene derivatives. ... 

Our final example is a base-labile 4-(phenyIsulfonyl)methyI-l,3-dioxolane protecting group for aldehydes and ketones. Protection is carried out by the reaction of diol 17.1 (obtained by dihydroxylation of allyl phenyl sulfone) with a carbonyl compound in the presence of pyridinium p-toluenesulfonate [Scheme 2.17). Cleavage is accomplished by treatment with DBU rm-ButyIdimethylsilyl ethers, p-toluenesulfonate esters, tetrahydropyranyl ethers, carboxylic esters and benzoates are well tolerated. A disadvantage to the use of 17.1 is the introduc-... 

Sulfones such as allyl-2-methylallyl sulfone and allyl phenyl sulfone and ketones such as 5-hexen-2-one, 2-allyl-2-methyl-l,3-cyclopentanedione, and meth-ylvinyl ketone have been copolymerized.Ethers such as 2,2-dimethyl-4-vinyldioxolane, ° 2-methyl-... 

In the presence of CH3-proazaphosphatrane catalyst, allyl phenyl sulfone readily dimerizes to give the product shown, for which only incomplete and inconclusive data exist in the literature. The dimer was shown from NMR spectral considerations to have the E configuration [66] (Scheme 5.44). 

Yu, Z. and Verkade, J.G. (2004) Catalytic dimerization of allyl phenyl sulfone in the presence of a proazaphosphatrane catalyst. Advanced Synthesis and Catalysis, 346, 539-541. 

For both sulfur dioxide and allyl phenyl sulfone plasma treatments, the LDPE samples were treated with plasma energies (W) of 5 W, 10 W, 30 W and 50 W. 

The surface elemental compositions of both the sulfur dioxide and allyl phenyl sulfone plasma treated samples were analyzed by a Perkin-Elmer PHI 5400 ESCA System with its packaged XPS software. The x-ray source was generated with an Mg anode energized at 15 kV and 300 W. The distance between the sample surface and the tip of the x-ray source anode was maintained constant at about 1.5 in. The aperture of the spherical capacitor electron energy analyzer was set at a diameter of 4 mm so that the area of the sample surface to be analyzed was about 1.3 mm in diameter. Both XPS survey and multiplex spectra of the plasma treated LDPE were collected at takeoff angles (0) of 10°, 30°, 45° and 75° with respect to the spherical capacitor electron energy analyzer, Angle-... 

Table 2. XPS results for the allyl phenyl sulfone plasma treated LDPE.

Figure 4. Sulfur atomic concentration vs. sin 0 from the allyl phenyl sulfone plasma treated LDPE at 5,10,30 and 50 W for 10 min. 

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