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Vinyl sulfides, alkylation

Formation of Sulfides. Thiols react readily with alkenes under the same types of conditions used to manufacture thiols. In this way, dialkyl sulfides and mixed alkyl sulfides can be produced. Sulfides are a principal by-product of thiol production. Mixed sulfides can be formed by the reaction of the thiol using a suitable starting material, as shown in equations 21, 22, and 23. Vinyl sulfides can be produced by the reaction of alkynes with thiols (38). [Pg.12]

Vinylic sulfides containing an a hydrogen can also be alkylated by alkyl halides or epoxides. This is a method for converting an alkyl halide RX to an a,P unsaturated aldehyde, which is the synthetic equivalent of the unknown HC=CH—CHO ion. Even simple alkyl aryl sulfides RCH2SAr and RR CHSAr have been alkylated a to the sulfur. ... [Pg.557]

Reaction of aliphatic aldehydes with H2S and TCS 14 at room temperature in the presence of pyridine leads to the adducts 596, which can be converted by NaH in DMF, via the adducts 597 and the intermediate thioaldehydes 598, into their sodium salts 599. These sodium salts 599 can be trapped by alkyl- or aUyl hahdes in up to 91% yield to give the vinyl sulfides 600 [147] (Scheme 5.47). [Pg.108]

The second cycloaddition substrate took to form of 91 (Scheme 1.9b), incorporating a vinyl sulfone dipolarophile. Beginning with cyano ketone 84, which was readily prepared from 1,5-dicyanopentane via a previously reported three-step sequence [45], condensation with thiophenol produced vinyl sulfide 85 in 84 % yield. Vinyl sulfide 85 underwent bromination in acetonitrile to afford bromo-vinyl sulfide 86 (86 %), which was then treated with isopropylmagnesium chloride [46] to effect metal-halogen exchange affording an intermediate vinyl magnesium bromide species. Subsequent alkylation with Mel in the presence of catalytic CuCN provided the alkylated vinyl sulfide 87 in 93 % yield. The nitrile within vinyl... [Pg.11]

Corresponding vinyl sulfides (5)7 and enamines (6)8 are accessible by the same Wittig reaction with alkyl thiotrifluoroacetates and disubstituted-trifluoroacetamides respectively. [Pg.226]

Whereas carbenoid character is definitely present in metalated alkyl vinyl ethers, lithiated alkyl and aryl vinyl sulfides and thioesters, which are easily available by hydrogen-lithium exchange, do not display carbenoid-typical reactions . They rather behave like nucleophilic reagents, so that their discussion is beyond the scope of this overview despite their utility in synthesis The same appiies to various derivatives of enamines, deprotonated in the vinyiic a-nitrogen position - . [Pg.856]

Strong bases readily eliminate thiol from vinylic sulfides. 1,2-Bis(alkyl- or arylthio)ethynes for example, react with two equivalents of BuLi or alkali amide to give metallated alkyl- or arylthioacetylenes and thiolates [24] ... [Pg.162]

Thioethers (sulfides) can be prepared by treatment of alkyl halides with salts of thiols (thiolate ions).7S2 R may be alkyl or aryl. As in 0-35, RX cannot be a tertiary halide, and sulfuric and sulfonic esters can be used instead of halides. As in the Williamson reaction (0-12), yields are improved by phase-transfer catalysis.753 Instead of RS ions, thiols themselves can be used, if the reaction is run in benzene in the presence of DBU (p. 1023).754 Neopentyl bromide was converted to Me3CCH2SPh in good yield by treatment with PhS in liquid NH3 at -33°C under the influence of light.755 This probably takes place by an SrnI mechanism (see p. 648). Vinylic sulfides can be prepared by treating vinylic bromides with PhS in the presence of a nickel complex,756 and with R3SnPh in the presence of Pd(PPh3)4.757 R can be tertiary if an alcohol is the substrate, e.g,758... [Pg.407]

Vinylic sulfides containing an a hydrogen can also be alkylated1516 by alkyl halides or epoxides. In one application, the ion 124, which can be prepared in three steps from epi-chlorohydrin, reacts with alkyl halides to give the bis(methylthio) compound 125,1517 which... [Pg.476]

Carbocyclization of m-alkcnyl-z-methoxybcnzy I lithiums to form five- or six-membered rings has been studied 101 the five-membered ring is formed with a cis-stereochemical relationship between the methoxy substituent and the adjacent methyl group. Intramolecular carbolithiation of vinyl sulfides at — 105°C in THF has been found to occur non-stereospecifically with regard to the newly formed C—Li centre.102. The stereochemistry of selective tandem Michael addition alkylation reactions of vinylphosphonates has been explored.103... [Pg.342]

Alkyl enol ethers and vinyl sulfides may also be oxidatively annulated onto electron-rich aromatic rings (Scheme 71)168. [Pg.1338]

Ketone synthesisAddition of an alkyl- or aryllithium to 1 forms an anion (a) that undergoes a Wittig-Horner reaction with an aldehyde to form a vinyl sulfide (2),... [Pg.555]

Alkenyl sulfides.6 An attractive route to vinyl sulfides involves cross coupling of a primary 9-alkyl-9-BBN with 1-bromo-l-phenylthioethene catalyzed by Pd(0) in the presence of a base, NaOH or K2HP04. This coupling can be extended to (E)- and... [Pg.318]

Under strictly anhydrous conditions which minimize competing protiodesilylation, (Z)-a-silyl vinyl sulfides with an co-carbonyl moiety attached to the S atom undergo a fluoride-promoted intramolecular cyclization which yields 2-alkenyltetrahydropyran-3-ols. The substrates are derived from (Z)-a-silyl enethiols by alkylation with co-halocarbo-nyl compounds (Scheme 157) <2000EJ02391>. [Pg.882]

The adducts (a) are converted by LDA, with elimination of C2H5OH, preferentially into the less substituted thioenolates (b), which afford vinyl sulfides (4) on alkylation. When the substitution pattern is similar (i.e., = H), a mixture of vinyl... [Pg.310]

This coupling is equally applicable to alkyl-, aryl-, and vinyllithium reagents. The products are obtained in generally good yield and in 98-100% isomeric purity. The reaction can also be used to prepare vinyl sulfides from vinyl halides and a lithium thiolate (equation II). [Pg.534]

Reaction of aryl vinyl ethers, however, invariably gives mixtures of diazetidines and oxadiazines. The ratio is mainly dependent on the nature of the substituent on the phenyl group and, in part, on the nature of the alkyl group of the dialkyl diazenedicarboxylate and the solvent substituents which enhance the nucleophilicity of the alkene and the electrophilicity of the diazene, and polar solvents that favor a polar mechanism, result in concurrent formation of the diazetidine as the predominant product and vice versa15, l< Similarly, diazetidines 7 and oxadiazines 8 are formed in comparable yields in the reactions of vinyl sulfides with dimethyl diazenedicarboxylate, the ratio is principally dependent on the nature of the sulfur substituent (aryl, alkyl)17. [Pg.951]


See other pages where Vinyl sulfides, alkylation is mentioned: [Pg.188]    [Pg.100]    [Pg.279]    [Pg.188]    [Pg.100]    [Pg.279]    [Pg.174]    [Pg.45]    [Pg.183]    [Pg.310]    [Pg.130]    [Pg.76]    [Pg.103]    [Pg.84]    [Pg.174]    [Pg.174]    [Pg.951]    [Pg.93]    [Pg.545]    [Pg.545]    [Pg.153]    [Pg.177]    [Pg.339]    [Pg.279]    [Pg.214]    [Pg.214]    [Pg.951]   
See also in sourсe #XX -- [ Pg.557 ]




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Vinyl sulfides

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