Allyl sulphides, oxidation

Allylic diphenylphosphine oxides undergo 1,3-dipolar cycloadditions with nitrile oxides to give A -isoxazolines (70) with ann -preferred stereoselectivities of up to 5 1.37 Separate reduction of y -and anti-(70) to the hydroxy amines (71), followed by Wittig-Horner elimination provides stereoselective syntheses of the homoallylic amines (72) (Scheme 9). A study of the effect of substituents on phosphorus on the diastereoselectivity in the cycloaddition of nitrones to vinylphosphine oxides (73) and sulphides (74) has been reported.38 In certain cases diastereoselectivities of >90% were achieved. 

The allyl sulphide (223) was obtained peracid oxidation furnished the sulphoxides (224). These sulphoxides rearranged on treatment with diethylamine to give, after deprotection, 7-hydroxy ... 

Kinetics of the oxidation of diallyl sulphide by singlet oxygen, and its inhibition by rubrene, have been reported. Isomerization studies in which the base-catalysed prop-2-eny 1-prop-1-enyl equilibrium for allyl sulphides, sulphoxides, and sulphones were compared have been undertaken, and isolated reports on this topic have been rationalized in terms of electronic distribution in the functional groups. 

Corey has reported a novel method for the introduction of two alkyl appendages at the carbonyl carbon of ketones. Ketones react with the anion of diethyl allylthiomethylphosphonate (155) to give vinyl allyl sulphides such as (156) heating in the presence of mercury(ii) oxide induces a thio-Claisen rearrangement to yield the aldehyde (157), which can be further elaborated by various oxidation-reduction sequences to give, for example, the spiro-enone (158). 

These include copolymers of propylene sulphide with 3-10% of allyl glycidyl thioether and which may be considered as a thio-analogue of the propylene oxide-allyl glycidyl ether rubber briefly mentioned in Section 19.5 ... 

Both inorganic and organic hypochlorites may be used for the oxidation of sulphoxides. The cheapest method involves the use of a commercial bleach, such as Chlorox . Such a method is indeed successful for unsaturated sulphoxides such as allyl methyl sulphoxide although the yields are generally low. Other sulphoxides may also be oxidized by this method, for example, dimethyl sulphoxide gave bis(trichloromethyl) sulphone in low yield . In some cases bis(dichloromethyl) sulphone was also isolated in very low yield. This oxidation procedure is also commonly used by organosulphur chemists for the removal of unwanted odours, caused by sulphoxides (and sulphides), from dirty glassware. 

ETHYLENE GLYCOL ETHYL MERCAPTAN DIMETHYL SULPHIDE ETHYL AMINE DIMETHYL AMIDE MONOETHANOLAMINE ETHYLENEDIAMINE ACRYLONITRILE PROPADIENE METHYL ACETYLENE ACROLEIN ACRYLIC ACID VINYL FORMATE ALLYL CHLORIDE 1 2 3-TRICHLOROPROPANE PROPIONITRILE CYCLOPROPANE PROPYLENE 1 2-DICHLOROPROPANE ACETONE ALLYL ALCOHOL PROPIONALDEHYDE PROPYLENE OXIDE VINYL METHYL ETHER PROPIONIC ACID ETHYL FORMATE METHYL ACETATE PROPYL CHLORIDE ISOPROPYL CHLORIDE PROPANE... 

Sulphoxides and selenoxides undergo syn elimination under thermal conditions. A 1,4-elimination of sulphenic acid from an allyl sulphoxide leads to dienes (equation 20)50. Precursor sulphoxides are generated by oxidation of corresponding sulphides. This reaction, however, did not give good results when applied to more complicated systems51. 

Grignard reagent (144) (R = H or Me) followed by oxidation gave the sulphone (145) which with allyl bromide afforded the acyclic C13 compound (146).92 This gave rise to p-ionone (142) or a- and p-irones (147) and (148), cyclization being achieved with H3P04. p-Cyclogeranyl phenyl sulphide (149) has been prepared... 

Recognition of the role of sulphoxides in the inhibition chain has resulted in several studies of the autoxidation of mono- and disulphides (see later). In addition to the work by Hargrave [84], Bateman et al. [88— 90] have studied the oxidation of monosulphides, unsaturated monosulphides and cyclo-hex-2-enyl methyl sulphide. Allylic and vinylic sulphides were found to be much more reactive than saturated sulphides, although the methylene group, rather than the allylic double bond, was suggested to be the primary reaction centre. Reactivities were compared for the percentage yield of sulphoxide (A) and for the yield of hydroperoxide (B), viz. 

Reactions.—Full details are now available" of the photochemical and thermal [1,3] phenylthio shifts of allyl phenyl sulphides [(73)- (74)]. Oxidation of such sulphides can lead to allyl alcohols through the known sulphoxide-sulphenate equilibrium with sulphenate trapping. 

Tin.—Allyltin compounds, especially under rhodium-complex catalysis, react with acyl chlorides to give allyl ketones or with aryl halides to give allylarenes. Bridgehead alkyl bromides are reduced on photolysis with Bu"3SnH, whilst the system (Bu"3Sn)20-Br2 oxidizes sulphides to sulphoxides. )V-(Alkoxycar-bonyl)amino-acids are obtained upon treatment of cyclic anhydrides with Bu3SnN3 and heating in an alcohol. ... 

The reactions shown above involve the main chain, but it is possible that sulphur-containing cross-links present in a vulcanizate are also sites for oxidative attack. Little is known about such processes except by analogy with simpler sulphides. The general thermal instability of allylic sulphoxides suggests that monosulphide cross-links may undergo the following reactions ... 

Photolysis of allyl pent-4-enyl sulphides such as (9) gave mixtures of five- and six-membered sulphur heterocycles via unsaturated thiyl radicals. Oxidative decarboxylation of the disulphide (10), and intramolecular trapping of the intermediate carbon radical to give the thiolan (11), indicated a biochemical pathway for the formation of the C(2)—S bond of penicillins. ... 

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