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Vinyltriphenylphosphonium salts

Yavari I, Hekmat-Shoar R, Zonuzi A (1998) A new and efficient route to 4-carboxymethyl-coumarins mediated by vinyltriphenylphosphonium salt. Tetrahedron Lett 39 2391-2392... [Pg.182]

Nucleophilic attack on the highly reactive 1 1 adducts produced in the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by 2-hydroxyketones leads to vinyltriphenylphosphonium salts, which undergo an intramolecular Wittig reaction to produce functionalized dialkyl 2,5-dihydrofuran-2,3-dicarboxylates in fairly high yields (Equation 61) <1998T9169>. [Pg.523]

The well-known approach to functionalized phosphorus ylides based on the three-component reactions of triphenylphosphine (TPP), dialkyl acet-ylenedicarboxylates (DAAD) and various EH-nucleophiles (E = N, O, S, C) stabilizing by protonation a reactive intermediate generated from the reaction of TPP and DAAD followed by addition of a conjugated base to the vinyltriphenylphosphonium salt formed, has continued to find application. When 2-bromoacetamide was used as a nucleophile in this reaction, a-amido phosphorus ylides (52) were formed, even despite the high reactivity of P(III) atom of phosphines towards alkyl halides and a-halocarbonyl compounds. Ethyl phenylcarbamate reacted in a similar way ((52), Y = OEt). The other series of stable a-amido phosphorus ylides (53) was produced from the above reaction with l-benzylidene-2-phenylhydrazines. The reaction of TPP,... [Pg.90]

A fairly general method for ring closure that involves vinyltriphenylphos-phonium halides has been developed. Two examples are shown. Comment on the mechanism of the reaction and suggest two additional types of rings that could be synthesized, using vinyltriphenylphosphonium salts. [Pg.70]

Vinyltriphenylphosphonium salts 128 were introduced by Schweizer et al. as early as 1964 for preparation of various types of heterocycles including dihydrofurans [75], pyrrolizidines [76] and 1,2-dihydroquinolines [77] from different nucleophilic oo-carbonylated anions 129. The latter, customarily prepared in situ, add to the vinyl group to generate a reactive oo-carbonylylide... [Pg.223]

The Schweizer synthesis of allylic amines is highly E-stereoselective when vinyltri-n-butylphosphonium bromide is used instead of the usual vinyltriphenylphosphonium salt. ... [Pg.32]

The sulfur of an a-mercapto-ketone (or a-mercapto-aldehyde [135]) will add to a vinyltriphenylphosphonium salt generating an intermediate ylide, e.g. 64, that undergoes an intramolecular Wittig reaction to produce a 2,5-dihydrothiophene... [Pg.35]

Additions to Vinylphosphonium Salts. Vinyltriphenylphosphonium bromide reacts with the enolate (141) to give a one-stage synthesis of the tricyclic ketone (142) (Scheme 6).135... [Pg.23]

In vinylic phosphonium salts, the jft-carbon is found to be substantially deshielded (A<5 = 22.4 ppm for the vinyltriphenylphosphonium bromide as compared with ethylene), although only a small inductive effect was expected. The extent of this was interpreted to be a consequence of pn-dn bonding between phosphorus and carbon39. This argument was used to identify structures when or 31PNMR spectra failed96. [Pg.57]

N-Alkyl-P-aminoethylphosphonium bromides, RHN(CH,CH2)P(QH,)3Br (1). These somewhat unstable salts can be obtained in high yield by reaction of primary amines and vinyltriphenylphosphonium bromide in CH,CN. [Pg.11]

The butadienylphosphonium salts (120) are formed in the reactions of phosphines with alkenoyl bromides. Diels-Alder cycloaddition reactions of vinyltriphenylphosphonium bromide with cyclopentadiene and anthracene derivatives have been used (together with conventional quaternization procedures)... [Pg.21]


See other pages where Vinyltriphenylphosphonium salts is mentioned: [Pg.205]    [Pg.135]    [Pg.295]    [Pg.896]    [Pg.135]    [Pg.295]    [Pg.896]    [Pg.239]    [Pg.31]    [Pg.135]    [Pg.108]    [Pg.106]    [Pg.91]    [Pg.117]    [Pg.205]    [Pg.135]    [Pg.295]    [Pg.896]    [Pg.135]    [Pg.295]    [Pg.896]    [Pg.239]    [Pg.31]    [Pg.135]    [Pg.108]    [Pg.106]    [Pg.91]    [Pg.117]    [Pg.126]    [Pg.150]    [Pg.126]    [Pg.18]    [Pg.126]    [Pg.38]    [Pg.20]    [Pg.459]   
See also in sourсe #XX -- [ Pg.214 ]




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