Methyl vinyl sulphide

In some cases, however, a high degree of stereoselectivity could be obtained even with pure triplet excited carbonyl compounds. In these cases, e.g., the photocycloaddition of benzophenone to several methyl vinyl sulphides 113, the intermediary triplet 1,4-biradical preferentially undergoes one of two possible cyclization modes after intersystem crossing (Sch. 34) [60]. 

Fig. 2. Reactivity of monomers with n-n conjugation (a) with styrene macroradical and (b) with methacrylate macroradical. O, Ethyl vinyl sulphide JV-vinylcarbazole , methyl vinyl sulphide.

Other miscellaneous additions reported include the photoaddition of thiocarboxylic acid to 3,4-diallyl-1,6-propano-1H,6H-3a-thia (S )-1,3,4,6-tetraazapentalene-2,5(3H,4H)-dithione, the Paterno-BUchi addition of methyl vinyl sulphides to benzophen-... 

The photolyses of H2Se,118 dimethyl sulphide, dibutyl sulphide, and methyl vinyl sulphide,119 and dimethyl sulphoxide,120 the role of concerted and hot biradical reactions in the photolysis of thietan and thietan-cyclopentadiene mixtures,121 and the photolysis of aromatic sulphur compounds122 have been reported. 

Photolysis (230—270 nm) of methyl vinyl sulphide yields products explicable in terms of the two homolytic cleavages... 

Cyclobutenylideneammonium salts, and hence cyclobutenones, are formed by the [2 + 2] addition of ketenimmonium salts to acetylenes. The reaction of dimethylketenimmonium tetrafluoroborate with the acetylenes gives the salts (205) in good yield, but the reaction is not highly regioselective. The salts are, themselves, excellent dienophiles, and may be used directly in reactions with dienes. The salt (206) gives the adducts (207) and (208) with butadiene or cyclopentadiene. Dimethyl-cyclobutenone (209) has also been prepared by the adcfition of dimethylketen to methyl vinyl sulphide, followed by methylation at sulphur and elimination of dimethyl sulphide. The ketone itself is a useful dienophile, but is less reactive than its imminium salt. The cyclobutenone (209) is functionally equivalent to terelactone which is an extremely reluctant dienophile. 

A condensation of vinyl sulphides of synthetic value involves the reaction of a-ethylthio-styrenes with an aldehyde in the presence of a Lewis acid catalyst to give 3-ethylthio-indenes. Regiospecific and stereospecific pentannelation i.e, fusion of a cyclopentane ring) of an alicyclic ketone involves arylthiomethylen-ation followed by base-catalysed addition to an aj8-unsaturated ester. a-Phenyl-thiobutenolides are less reactive Michael acceptors than their sulphoxide counterparts, and /SjS-dichlorovinyl sulphides are less reactive in electrophilic reactions than their oxygen counterparts. Dimerization of aryl a-cyanovinyl sulphides occurs more readily than that of alkyl analogues, since the intermediate 1,4-diradical ArSC(CN)CH2CH2d(CN)SAr, which cyclizes to the cyclobutane, is more stable. Products obtained by photolysis of methyl vinyl sulphide are accounted for by homolysis of both vinyl—S and methyl—S bonds. The kinetics of catalysed cis-trans isomerization of aryl vinyl sulphides have been studied. ... 

Morris, T. H., Smith, E. H., and Walsh, R., Oxetane synthesis methyl vinyl sulphides as new traps of excited benzophenone in a stereoselective and regiospecific Paterno-Biichi reaction, J. Chem. Soc., Chem. Commun., 964, 1987. 

METHYL ETHYL SULPHIDE N-PROPYL AMINE ISOPROPYL AMINE TRIMETHYL AMINE MALEIC ANHYDRIDE VINYL ACETYLENE... 

Krief and coworkers have also shown that vinyl sulphides are useful traps for the intramolecular carbolithiation reactions. Interestingly, as the sulphide substituent can be reductively removed, the cyclization reactions of benzyllithiums derived from 73 and 75 are synthetically equivalents to cyclizations onto disubstituted double bonds, giving rise by complementary routes to compound 74 (Scheme 20)46. Like the corresponding carbolithiation reactions onto monosubstituted alkenes they are highly stereoselective but dependent on the solvent used, i.e. the derivatives in which the methyl- and the phenylthio groups are cis (THF) or trans (pentane) one to the other are selectively formed. 

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. 

This reaction can be promoted by the use of dimethyl sulphide as a catalyst (Chalcogeno-Baylis-Hillman reaction) in the presence of stoichiometric amounts of TMSOTf in the case of the reaction between methyl vinyl ketone andp-nitrobenzaldehyde a 2 1 adduct was isolated (eq 72), with incorporation of two units of ketone into the final product. ... 

Vinyl bromides react with copper(i) thiolates, both aliphatic and aromatic, to give vinyl sulphides. Vinyl bromides studied include ]8-bromostyrene and l-bromo-2-methyl-l-propene. This method of synthesis of thioethers is claimed to be superior to that using sodium thiolates and most other reported methods . 1,2-Dibromoethylene gives a mixture of cis (18%) and Irons (42%) 1,2-diphenylthioethylene with copper(i) benzene-thiolate, but with copper(i) ethanethiolate ethylthioacetylene is formed with the elimination of hy ogen bromide , ... 

Aliphatic thiols have been subjected to i.r., Raman, and microwave spectroscopic studies. Methyl and ethynyl groups are gauche in ethyl vinyl sulphide, as judged from microwave data. I.r./Raman studies of aliphatic sulphides and disulphides similarly include interpretation in terms of conformation or bonding. Comparative i.r./Raman studies of dimethyl sulphide, sulphoxide, and sulphone and the corresponding diphenyl series have been described. I.r. spectra of selenuranes and sulphones and sulphimides have been inter-... 

Electron Diffraction.— Bond-length and bond-angle data have become available for trifluoromethanethiol, phenyl vinyl sulphide, dimethyl disulphide, ethyl methyl disulphide, dimethyl sulphurdi-imide, and benzenesulphonyl chloride. ... 

Raasch has extended his studies of the reactivity of bis(trifluoro-methyl)thioketen (141). Scheme 8 gives a survey of the reactions that have been carried out. Thus common nucleophilic agents such as alcohols, thiols, primary, and secondary amines, etc., react with (141) with conservation of the C=S double bond, whereas the C==C double bond remains in the products of the reactions of (141) with certain ethers, dimethylaniline, and hydrides of tin and silicon. Compound (141) reacted with a variety of olehnic substances in accordance with the general ene-reaction formalism, yielding allyl vinyl sulphides (148). The formation... 

Poly(ethylene terephtlhalate) Phenol-formaldehyde Polyimide Polyisobutylene Poly(methyl methacrylate), acrylic Poly-4-methylpentene-1 Polyoxymethylene polyformaldehyde, acetal Polypropylene Polyphenylene ether Polyphenylene oxide Poly(phenylene sulphide) Poly(phenylene sulphone) Polystyrene Polysulfone Polytetrafluoroethylene Polyurethane Poly(vinyl acetate) Poly(vinyl alcohol) Poly(vinyl butyral) Poly(vinyl chloride) Poly(vinylidene chloride) Poly(vinylidene fluoride) Poly(vinyl formal) Polyvinylcarbazole Styrene Acrylonitrile Styrene butadiene rubber Styrene-butadiene-styrene Urea-formaldehyde Unsaturated polyester... 

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... 

Diaryl amines, ethers or sulphides, or their aryl vinyl analogues, provide another 6-electron system related to stilbene, but for these a pair of electrons is provided by the single heteroatom (ArXAr or ArXC=C). With dtaryl compounds the initial photocydized product is a zwitterion that undergoes a proton shift to give, for example, N-methyl-4a,4b-dihydrocarbazole from methyldiphenylamine, with subsequent oxidation to N-methylcarbazole (3.74). With the aryl vinyl analogues the product after the proton shift can normally be isolated (3.751. An especially useful variation of this reaction employs... 

Phenyl phenacyl sulphide has also been reported to be a good photoinitiator for the polymerization of methyl methacrylate, acrylonitrile, styrene, and vinyl acetate (30). 

CIC the earthy odour of fresh potatoes is represented by 2-isopropyl-3-methoxy pyrazine. This earthy note is supported by the mushroom character of l-octen-3-ol. The key component of boiled potatoes is 3-(methylthio)-propanal, balanced with dimethyl sulphide. The high reaction temperatures in baked and fried potatoes start the Maillard reaction to form mainly heterocyclic components 2-ethyl-3,5-dimethyl pyrazine, 2-ethyl-6-vinyl pyrazine, 5-methyl-6,7-dihydro-(5H)cyclopenta-pyrazine, 2-acetyl-l,4,5,6-tetrahydro-pyridine are responsible for the roasted, nutty cracker-like flavour. The heat-induced degradation of the potato lipids and the frying oil imparts a fatty, tallowy character to the french fried potatoes. (E,E)-2,4-Decadienal, 2-octenal, octanoic acid and decanoic acid are main contributors to this fatty note. 

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