Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Sulphoxides vinyl

The reaction of the phenylsulphinyl allylic lithium a-carbanion 342 with oxiranes was found by Guittet and Julia to give, after rearrangement and desulphurization, dihydroxy-dienes 343427 (equation 197). Demoute and coworkers have described the alkylation reaction of a very sophisticated 2-alkenyl sulphoxide 344 as a part of the total synthesis of a juvenile hormone 345428 (equation 198). Since the allylic sulphoxide carbanion has an ambident character, the alkylation may occur sometimes also at the y-position. This direction of alkylation is observed in the case of acyclic allylic sulphoxide anions 346, and results in the formation of the corresponding allylic sulphoxide 347 and vinylic sulphoxide 348423 (equation 199). [Pg.313]

TABLE 24. Synthesis of vinyl sulphoxides 443 from a-phosphoryl sulphoxides 442... [Pg.333]

Mercaptanes add easily to divinyl sulphoxide in the presence of catalytic amounts of bases, giving / -alkylthioethyl vinyl sulphoxides 545 and / , / -di(alkylthioethyl)sulphoxides 546 (equation 344). When an excess of divinyl sulphoxide is applied the reaction can be stopped at the stage of monoaddition63 5-636. [Pg.353]

TABLE 26. Michael additions to aryl vinyl sulphoxides... [Pg.354]

Dialkyl cuprates may also be added to aryl vinyl sulphoxides and the resulting a-sulphinyl carbanions can be treated with various electrophiles such as aldehydes, ketones and alkyl halides (equation 350)643. [Pg.355]

Halogenovinyl sulphoxides 551 react with nucleophiles to give -substituted vinyl sulphoxides 552. The first step in the reaction is a Michael addition, followed by an elimination of a halide anion605,627 (equation 351). [Pg.355]

Alkynyl sulphoxides 553, 554 also behave as Michael acceptors and afford the corresponding jS-substituted vinyl sulphoxides upon treatment with nucleo-philes605,644-646 (equations 352 and 353). [Pg.355]

For a recent discussion on the stereochemical aspects of the Diels-Alder reaction with vinyl sulphoxides see References 662, 663. It should be pointed out that vinyl sulphoxides can be considered in [2 + 4]-cycloadditions as acetylene synthons since the sulphinyl moiety may be removed from the product by sulphenic acid elimination. Paquette and coworkers took advantage of this fact in the synthesis of properly substituted anthracenes 562664, (equation 360). [Pg.358]

The cycloaddition of nitrile oxides 574 to vinyl sulphoxides usually produces a mixture of regio- and diastereoisomers. Their ratio is dependent on the nitrile oxide used and the configuration around the double bond in the starting sulphoxide (equation 365)673. [Pg.360]

On the other hand, a very high asymmetric induction was observed in the 1,3-dipolar cycloaddition of (/ )-( + )-p-tolyI vinyl sulphoxide 578 with acyclic nitrones. The reaction... [Pg.360]

Aryl vinyl sulphones, reactions of 646 Aryl vinyl sulphoxides 620 optical resolution of 287 reactions of 354, 355, 360, 361, 621 Asscher-Vofsi reaction 189 Asymmetric induction 625 Asymmetric oxidation 72-78 Asymmetric reduction 78, 79 Asymmetric synthesis 824-846 Atomic orbitals 2, 3 Azetidinones 790, 791 ot-Azidoaldehydes, synthesis of 811 Azidosulphones, photolysis of 883, 884 Azosulphones, photolysis of 879 Azoxysulphones, photolysis of 879 1-Azulyl sulphoxides, synthesis of 265... [Pg.1197]

Keywords acrylates, acrylamides, fumarates, a, -unsaturated ketones, vinyl ethers, vinyl sulphoxides, chiral dienophiles, chiral dienes, chiral catalysts polymer-supported chiral Lewis acids... [Pg.312]

Allyl p-tolyl sulphoxide 535 reacts with sodium methoxide in methanol by initial prototropic isomerization and subsequent addition of methanol to give 536 (equation 333). Protic solvents are photochemically incorporated by the open chain olefinic bond of trans methyl )S-styryl sulphoxide 537 in a Markovnikov regiospecificity (equation 334). Mercaptanes and thiophenols add to vinyl sulphoxides in a similar manner (compare also Reference 604 and Section IV.B.3) to give fi-alkylthio(arylthio)ethyl sulphoxides 538 (equation 335). Addition of deuteriated thio-phenol (PhSD) to optically active p-tolyl vinyl sulphoxide is accompanied by a low asymmetric a-induction not exceeding 10% (equation 336) . Addition of amines to vinyl sulphoxides proceeds in the same way giving )S-aminoethyl sulphoxides in good to quantitative yields depending on the substituents at the vinyl moiety When optically active p-tolyl vinyl sulphoxides are used in this reaction, diastereoisomeric mixtures are always formed and asymmetric induction at the p- and a-carbon atoms is 80 20 (R = H, R = Me) and 1.8 1 (R = Me, R = H), respectively (equation 337) ... [Pg.351]

Nucleophilic addition to allenyl sulphoxides 547 proceeds across the a, /(-double bond to produce the corresponding )3-substituted allylic sulphoxides which undergo readily a [2,3]-sigmatropic rearrangement affording substituted allyl alcohols (equation 345). Under proper basic conditions, the initially formed allylic sulphoxides can rearrange to the corresponding vinyl sulphoxides which can be elaborated to 2,4-dienones 549 (equation 346) and a-ketosulphoxides (equation 347) . ... [Pg.353]


See other pages where Sulphoxides vinyl is mentioned: [Pg.236]    [Pg.287]    [Pg.322]    [Pg.331]    [Pg.332]    [Pg.334]    [Pg.346]    [Pg.349]    [Pg.351]    [Pg.352]    [Pg.353]    [Pg.353]    [Pg.357]    [Pg.360]    [Pg.1195]    [Pg.1207]    [Pg.1208]    [Pg.1210]    [Pg.236]    [Pg.287]    [Pg.322]    [Pg.331]    [Pg.334]    [Pg.334]    [Pg.346]    [Pg.349]    [Pg.353]    [Pg.357]    [Pg.360]   
See also in sourсe #XX -- [ Pg.620 , Pg.621 ]




SEARCH



Aryl vinyl sulphoxides

Aryl vinyl sulphoxides reactions

Sulphoxidation

Sulphoxide

Sulphoxides

Thionocarbonates vinyl sulphoxides

Vinyl sulphoxides cycloaddition

Vinyl sulphoxides nucleophilic addition

Vinyl sulphoxides reactions

Vinyl sulphoxides rearrangement

Vinyl sulphoxides synthesis

© 2024 chempedia.info