Allyl sulfides protons

The simple thietes are unstable with respect to treatment with strong bases or nucleophiles. Proton abstraction from thiete was observed via deuterium-proton exchange with CH3OD-CH3O it appeared to be faster than exchange with allyl sulfide, but slower than that with phenylacetylene. " The thiete, however, could not be recovered from the reaction mixture. Treatment of thiete with potassium t-butoxide did not result in incorporation of deuterium when the reaction was quenched with D2O treatment with potassium 1-methylcyclohexoxide resulted in the rapid disappearance of the nmr absorption of the protons of the thiete. ... 

The NMR spectrum of a polystyrene macromonomer, 19, prepared by chain transfer with allylic sulfide 17, is shown in Figure 4. The end group olefinic protons appear at 6 -5.1 and 4.7 ppm and the t-butyl end group at 6 -1.2 ppm. (The sharp signals at 5 2.0 and 2.2 ppm are due to ds-acetone and water respectively, present in the solvent). 

Stereoselective preparation of ( )-allyl alcohols via radical elimination from anti-j-phenylthio-P-nitro alcohols has been reported.154 The requisite anti-P-nitro sulfides are prepared by protonation of nitronates at low temperature (see Chapter 4), and subsequent treatment with Bu3SnH induces anti elimination to give (E)-alkenes selectively (see Eq. 7.112). Unfortunately, it is difficult to get the pure yyw-P-nitro sulfides. Treatment of a mixture of syn- and anti-P-nitrosulfides with Bu3SnH results in formation of a mixture of (E)- and (Z)-alkenes. 

A novel tandem process has been reported " for the preparation of allylic amines, ethers, and sulfides from a-bromo-a, jS-unsaturated sulfones. The process is believed to proceed via an initial conjugate addition followed by proton exchange and Ramberg-Backlund rearrangement (see Scheme 75). A new variant of the Ramberg-Backlund reaction has been described in which a, /f-epoxy sulfones (319), on treatment with base, are converted into a range of mono-, di-, and tri-substituted allylic alcohols (320). 

Competing reactions to addition to a-hetero-substituted alkenes are metallation of vinylic or allylic protons (see 5.5.2.3.2) and cleavage of the carbon-hetero-element bond (see 5.5.2.2.1.). a-Metallations occur with vinylic chlorides, fluorides and ethers no addition of RLi occurs with vinyl fluorides, chlorides or ethers. For vinylic sulfides and selenides, whether metallation or addition (or even carbon-heterobond cleavage) occurs depends on the conditions and reagents. Addition of RLi (R = Et or n-Bu, not Ph) occurs to aryl vinyl sulfides ... 

The breath of a test person was analyzed over a time period of about 30 hours by means of proton-transfer-reaction mass spectrometry [55]. After ingestion of cut raw garlic, tiie components allyl metfiyl sulfide, allyl methyl disulfide, diallyl sulfide, diallyl disulfide, diallyl trisulfide, dimethyl sulfide, and acetone were detected. While the concentrations of allyl mediyl disulfide, diallyl sulfide, diallyl disulfide, and diallyl trisulfide reached maximum concentration shortly after ingestion of garlic and declined to baseline values within the next 2-3 h, concentrations of allyl methyl sulfide, dimethyl sulfide, and acetone increased much more slowly... 

A probable mechanism for the thiocarbonylation of allylic alcohols is outlined in Scheme 3. It is well-known that Pd(OAc>2 is easily reduced to Pd(0) in situ in the presence of phosphine ligands and carbon monoxide. Oxidative addition of protonated allylic alcohol to Pd(0) gives the tr-allylpalladium complex A, which may undergo substitution of H2O by SPh to form the tr-allylpalladium sulfide complex B. Insertion of CO into B affords the acylpalla-dium complex C. Reductive elimination of Pd(0) would form the /3,-y-unsaturated thioesters. 

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