Allenic Sulphides

Allenic Sulphides.—This short section is mainly concerned with alka-l,2-dienyl sulphides and related compounds. The reaction of Cl2C=CClC=CPh or of PhCCl=CClC=CCl with an alkanethiolate gives (RS)2C=C=C=CPhSR, while 

Akiyama, S. Nakatsuji, T. Hamamura, M. Kataoka, and M. Nakagawa, Tetrahedron Lett., 1979, 2809. 

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The 2-vinylpyrrolidines 321 are formed in up to 99% diastereomeric excess by the ring closure of the allenic sulphides or sulphoxides 320 (R = PhS or PhSO), induced by silver(I) ions376. 

Books published recently include several that are wholly devoted to organosulphur compoundsand others " in which specific chapters are relevant to the coverage in this chapter. Reviews have appeared that deal with applications of organosulphur compounds in synthesis " (including uses of yff-keto-sulphides, vinyl sulphones, and vinyl sulphides ) and the synthesis of organosulphur compounds,sulphenyl compounds, indolethiols, allenic sulphides and sulphenamides, organosilyl sulphides, selenides, and tellurides, optically active... 

Allen PL, Hickling A (1957) Electrochemistry of sulphur. Part 1 - Overpotential in the discharge of the sulphide ion. Trans Faraday Soc 53 1626-1635... 

Archer SD, Gilbert FJ, Allen JI, Blackford J, Nightingale PD (2004) Modelling of the seasonal patterns of dimethyl-sulphide production and fate during 1989 at a site in the North Sea. Can J Fish Aquat Sci 61 765-787... 

Alkylation of the sulphone (111) with Bu"Li-Me3SiCH2l gave the /8-silyl-sulphone (112) which with Bu NF gave ° 3-methylene-5a-cholestane (113). Alkenyl sulphoxides, such as (114), were reduced to the alkenyl sulphides, without double-bond isomerization, using EtNlgBr-Cul " and the terminal allene (115) was prepared by treatment of (114) with LTMP. Reaction of... 

A new method for the selective demethylation of alkyl methyl phosphates employs a mixture of dimethyl sulphide and methanesulphonic acid. Boron trifluoride etherate catalyses the regio- and stereo-specific alkenylation of phenolic ethers by diisopropyl prenyl or geranyl phosphates (84) in low to moderate yields. 2-(Diethoxyphosphinyl)-1,3-butadienes, e.g., (85), are cleaved by organocopper reagents in some cases this reaction is accompanied by alkylation and rearrangement to an allene structure. ... 

The concurrent release of sulphide (AVS) and reactive metals (SEM) during extraction with HCl cannot be considered as evidence that those particular metals were bound by sulphide in the sediment (Allen et al., 1993). Various studies show that... 

Thermal [2,3] sigmatropic rearrangement of the sulphonium ylide (114) gives a 54% yield of a mixture of four isomeric products, the major (70%) of which is the allenic thioether (115), a species which contains the entire artemisyl carbon skeleton hydrolysis with mercuric chloride then leads to artemisia ketone in 80% yield. The second route involves methallylation of the methyl thioacetal monoxide (116), the unstable intermediate (117) on distillation being transformed into the trienic sulphide (118). The latter species on hydrolysis gives artemisia ketone in 57% yield. 

This reaction also yields both five and six-membered cyclic products, but has been shown to consist of two parallel processes . Prop-2-ynyl phenyl sulphide (117) on heating initially isomerizes to phenyl allenyl sulphide (118) and both 117 and 118 undergo the thio-Claisen rearrangement to the allenic (119) and acetylenic (120) thiols respectively. Subsequent cyclization yields the final products, 2H-thiachromene (121) and 2-methyl-benzothiophene (122). 

Dunleavy M, Allen GC, Paul M (1992) Characterization of lanthanum sulphides. Adv Mater 4 424 27... 

An inverse electron demand Alder-Ene reaction has been reported in which a nitrilium ion acts as the ene and an arene as enophile. The reaction occurred at room temperature and was proposed to be a double Alder-Ene reaction. The first step provided compound 133, which could undergo a stepwise addition of the vinyl sulphide to the azonia-allene followed by elimination or alternatively, a second concerted Alder-Ene type mechanism was suggested. The heterobicycle 134 was isolated in 90% yield. 

A new thiophen synthesis is based on deprotonation and cyclization of the resultant carbanion (65) of a keten dimethylthioacetal. Other applications of cr-(phenylthio)- or cr-(alkylthio)-alkyl-lithiums include preparations of disparlure (the sex pheromone of the gypsy moth) and other chiral epoxides,of an anti-peptic-ulcer diterpene from Croton sublyratus, of carbene-thiometal chelates through reaction with fCr(CO)gl or fW(CO)jl, of olefins via )ff-hydroxy-sulphides, and of Michael adducts of enones. In other work, the chiral solvent l,4-dimethylamino-2,3-dimethoxybutane is employed in enantioselective addition reactions of cr-thio-carbanions with ketones and Michael acceptors. a,P -Elimination of cr-thio-carbanions such as (66) provides a useful synthesis of olefins, and a 2-(lithiomethylthio)-A -oxazoline (67) has been used to prepare a C-labelled thiiran for a microwave study of the valence tautomerism of allene episulphide. ... 

Allenyl-lithium reagents, generated by metallation of allenic hydrocarbons or from haloallenes by halogen-metal exchange, react with various electrophiles with retention of the allenic structure to give functionalized allenes. High yields of allenylsilanes and sulphides, allenic acids and dialkylamides, and fi-allenic alcohols are available by this method. However, additions to ketones are less satisfactory since propargylic alcohols are formed in some cases. 

Allen Crenshaw (1912) Allen, E.T. Crenshaw, J.L. The Sulphides of Zinc, Cadmium and Mercury Their Crystalline Forms and Genetic Conditions American Journal of Science 34 (1912) 341-396... 

Indenes can be synthesized via intramolecular hydroarylation of propargyl acetates catalyzed by NHC gold(I) complexes [127, 128]. The formation of the indenes proceeds via a 1,3-shift to form an allene, followed by the hydroarylation (Scheme 1.8). Notably, this reaction requires strictly anhydrous conditions, because conjugated enones and enals are isolated in the presence of water [129]. Related transformations include reaction with propagyl sulphides or dithioacetals. 

Reactions of Ethers.—In a recent report, allylic ethers (and sulphides, etc.) have been shown to be reduced to alkenes, with retention of the position and geometry of the double bond, by lithium triethylborohydride-Pd(PPh8)4. Deprotonation of propargyl ethers can be used to make allenic ethers and some a-substituted derivatives (Scheme 38). ... 

Addition of thiols to diketen gives y-alkylthio-jS-butyrolactones, which suffer rearrangement, or loss of CO2 to give the allyl sulphide. Radical addition of thiophenol to the allenes (12) and (12a) gives vinyl and allyl sulphides (13) and (14), respectively." The radical pathway is normally... 

Dimethylprop-2-ynylsulphonium bromide isomerizes to the allene, which is susceptible to nucleophilic addition, giving a product mixture including the demethylation product MeSCH=CMeX (X = nucleophile). (+)-l-Adamantyl allyl ethyl sulphonium fluoroborate undergoes [2,3]-sigmatropic rearrangement to give a mixture of adamantyl ethyl and allyl sulphides and (-)-(R)-l-adamantyl pent-4-en-2-yl sulphide,i.e. with inversion at carbon chirality is transferred from S to C with at least 94% optical induction. 

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