Vinyl reaction

Dehalogenation of monochlorotoluenes can be readily effected with hydrogen and noble metal catalysts (34). Conversion of -chlorotoluene to Ncyanotoluene is accompHshed by reaction with tetraethyl ammonium cyanide and zero-valent Group (VIII) metal complexes, such as those of nickel or palladium (35). The reaction proceeds by initial oxidative addition of the aryl haHde to the zerovalent metal complex, followed by attack of cyanide ion on the metal and reductive elimination of the aryl cyanide. Methylstyrene is prepared from -chlorotoluene by a vinylation reaction using ethylene as the reagent and a catalyst derived from zinc, a triarylphosphine, and a nickel salt (36). 

Pyrazole, 3,4,5-tris(trifluoromethyl)-synthesis, 5, 282 Pyrazole, vinyl-reactions, 5, 261 Pyrazole, 1-vinyl-polymerization, 1, 279... 

The parent compound in this series, that is, the agent substituted by a vinyl group, is obtained by direct vinylation. Reaction of the monosubstituted barbiturate, 129, with ethylene at elevated temperature and pressure in the presence of a zinc catalyst affords butylvinal (110). ... 

Figure 22 Proposed modification scheme for the surface complex during vinylation reaction.

Satoh T, Miura M (2007) Catalytic Arylation and Vinylation Reactions Directed by Anionic Oxygen Functions via Cleavage of C - H and C - C Bonds. 24 61-84 Savoia D (2005) Progress in the Asymmetric Synthesis of 1,2-Diamines from Azomethine Compounds. 15 1-58... 

Telluroesters have also been employed as starting materials in teUuro vinylation reactions. Thus, by treatment of telluroesters with aryl propiolates in the presence of KjCOj, (Z)-/(-acyltellurocinnamates are formed in high yields. This procedure involves the addition of potassium aryltellurolate anions derived from the telluroesters. " ... 

In the presence of this catalyst, the catalytic vinylation reactions of Eqs.(15) and (16) are largely suppressed. 

Another way to produce acetic acid is based on a carbonylation of methanol in the so called Monsanto process, which is the dominant technology for the production of acetic acid today [15]. Acetic acid then is converted to VAM by addition of ethylene to acetic acid in the gas phase using heterogeneous catalysts usually based on palladium, cadmium, gold and its alloys (vinylation reaction 3 in Fig. 2) [16] supported on silica structures. 

Fig. 21. Heck-type vinylation reaction with PolyHIPE-supported Pd catalyst...

Among the characterized metal homoenolates, only zinc homoenolate of alkyl propionate undergoes substitution reactions with electrophiles under suitable conditions. Two types of metal catalysts, copper(I) and metals of the nickel triad (e.g. Pd), have successfully been used to effect allylation, arylation, and vinylation reactions. 

A very practical route to zinc homoenolate involves reduction of 3-iodoesters with zinc/copper couple in the presence of a polar solvent, e.g. DMF, DMA [49] Eq. (51). The nature of the species obtained in this approach is not well-defined, but appears to be essentially the same as the one obtained along the siloxycyclo-propane route. Acylation, arylation, and vinylation reactions have been reported. 

This vinylation reaction was used in a two-step synthesis of 6 in about 60% yield from cyclohexenone. This product is of interest because the derived triene (7) is converted upon heating into the 1,6-cyclododecadiene 8 by a Cope rearrangement followed by a Claisen rearrangement,4... 

Imidazole, l,2,5-trimethyl-4-nitro-mass spectra, 5, 359 Imidazole, 1-trimethylsilyl-reactions, 5, 454 with acid chlorides, 5, 391 Imidazole, 1-trimethylstannyl-reactions, 5, 454 Imidazole, 2,4,5-trinitro-reactions, 5, 98 synthesis, 5, 395 Imidazole, 1,2,4-triphenyl-UV spectra, 5, 356 Imidazole, 1,2,5-triphenyl-UV spectra, 5, 356 Imidazole, 2,4,5-triphenyl-chemiluminescence, 5, 381, 406 irradiation, 5, 433 oxidation, 5, 376, 406 photochemical addition reactions, 5, 421 synthesis, 5, 467, 483 UV spectra, 5, 356, 357 Imidazole, 1-trityl-rearrangement, 5, 377 Imidazole, vinyl-Michael addition, 5, 437 polymers, 1, 281 Imidazole, 1-vinyl-reactions, 5, 450 thermal rearrangement, 5, 450 Imidazole, 2-vinyl-oxidation, 5, 437 Imidazole, l-(D-xylofuranosyl)-synthesis, 5, 491 277-Imidazole, 2,2-dialkyl-rearrangement, 5, 422 277-Imidazole, 4,5-dicyano-2,2-dimethyl-synthesis, 5, 472... 

Catalytic oxy-palladation is an extremely useful method for the synthesis of functionalized THF and tetrahydropyran moieties. This reaction is brought about simply by treating a 1,4- or 1,5-hydroxy alkene with 0.1 mol-eq of Pd(II) salts and copper(I) chloride in DMF, with oxygen (equation 181)655. If this reaction is carried out in the presence of carbon monoxide in methanol, then an ester moiety is introduced into the product molecule (equation 182)656-658. If an alkene is introduced in place of the CO, then a tandem vinylation reaction also takes place (equation 183)659. 

In 1971, a year before the groups of Corriu and Kumada [5] independently reported the groundbreaking work on the topic of nickel-catalyzed cross-coupling reactions of aryl and vinyl halides with Grignard reagents, Tamura and Kochi described an iron-catalyzed vinylation reaction of Grignard reagents with vinyl halides (Scheme 5.1) [6]. 

Chen, S.-H. On the Stille vinylation reactions with a-styryltrimethyltin. Tetrahedron Lett. 

Clarke recently published the first microwave-accelerated Hiyama coupling [163,164]. It was noted that the availability and nontoxic attributes of the organosilicon reactants make them very attractive in synthesis, but their low nucleophilicity limits their potential. Microwave heating allowed aryl bromides and activated aryl chlorides to react under palladium catalysis using an electron-rich N-methyl piperazine/cyclohexyl phosphine ligand (Scheme 75). A vinylation reaction with vinyltrimethoxysilane was also reported [164],... 

Only a few additional examples of intermolecular photochemical vinylations of (hetero)aromatic compounds have been forthcoming. Coupling products are formed in the irradiation of dichloro- and dibromo-A-methylmaleimide in the presence of 1,3-dimethyluracils341 and of 3-bromocoumarin in the presence of naphthalene, phenanthrene, 1-methylpyrrole and other aromatic compounds342. The former reaction is accompanied by cyclobutane adduct formation, which is the mode of reaction of A-methylmaleimide itself. The mechanism of these vinylation reactions is not clear, but most probably an exci-plex (cf equation 20a) or a charge-transfer complex (cf equation 20b) is involved. 

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