Vinylmagnesium halide

Vinyl acetate, 57,117 Vinylacetic acid, 56,49 ct-Vinylbenzyl alcohol, 56, 106 Vinyl bromide, 58,152, 155, 157 Vinyl chloride, 58,133 Vinylene carbonate, 57, 117 Vinylmagnesium halides, 59,92 2-Vinylpytidine, 58, 73 Vinyl sulfides, 59, 202... 

Allylic substitution reactions catalyzed by metalacyclic iridium-phosphoramidite complexes form branched products from linear allylic esters with high regioselec-tivity. However, reactions with racemic, branched allylic esters would be particularly valuable because they are readily accessible from a wide array of aldehydes and vinylmagnesium halides. However, iridium-catalyzed allylic substitution reactions of branched allylic esters have so far occurred with low enantioselectivities [45, 75]. 

Nakamura and coworkers showed that the addition reaction of zincated hydrazone to vinylmagnesium halide as electrophile gives the s/r1-geminated organodimetal reagent (Scheme 37). The reaction pathway can be considered as a metalla-aza-Claisen-type... 

The synthetic method (b) combines the formation of a primary or secondary alkynol [from formaldehyde or an aldehyde respectively and an organometallic acetylenic reagent (Section 5.4.2, p. 532)] with the semihydrogenation of the triple bond to a double bond. As noted in Section 5.2.2, p. 493, appropriate selection of catalyst is necessary in the hydrogenation step to ensure the formation of either the ( )- or the (Z)-isomer. The specific formation of the allylic alcohol, CH2=CH-CH(OH),R, is from a vinylmagnesium halide (Expt 6.41) and an aldehyde. 

Gomtsyan, A. Org. Lett. 2000, 2, 11. For a reaction with methyl esters with an excess of vinylmagnesium halide and a copper catalyst to give a 3-butenyl ketone by a similar acyl substitution-Michael addition route, see Hansford, K.A. Dettwiler, J.E. Lubell, W.D. Org. Lett. 2003, 5, 4887. Gomtsyan, A. Koenig, R.J. Lee, C.-H. J. Org. Chem. 2001, 66, 3613. 

Vinyl halides. Vinyl halides, even the iodide, are not convertible to Grignard reagents by the usual procedure, but Normant found that vinyl chloride and vinyl bromide readily form vinylmagnesium halides in solution in tetrahydrofurane (THF) or in a diether of di- or triethylene glycol. See review. ... 

Vinyl laurate, 648-649, 1271 Vinyllithium, 1250, 1273-1274 Vinylmagnesium bromide, 213, 332 Vinylmagnesium chloride, 415 Vinylmagnesium halides, 418 2-Vinylthiophene, 960 Vinyl triphenylphosphonium bromide, 1274-127S Viscolizer, 434... 

Normant reagents. Vinylmagnesium halides that were previously unavailable are now prepared by reacting the parent vinyl halides with magnesium in tetrahydrofuran. These compounds are called Normant reagents and behave like typical Grignard reagents. 

Reactions of nitroarenes with vinylmagnesium halides give indoles (the Bartoli reaction).607 Site selectivity problems may be avoided by temporarily installing a bromine ortho to the nitro group (Eq. 187).608... 

DL-Valeric acid, 369 Vanadium oxyacetylacetonate, 456 Vanadyl acetylacetonate, see Vanadium oxyacetylacetonate Vanillin, 217 Veratrole, 116 a-Vetivone, 306 Vilsmeir reaction, 129 Vinylacetic acid, 428 crr-Vinylalanes, 141, 142 mww-Vinylalanes, 141, 142 Vinyl azides, 100 Vinyl halides, 142 Vinylidinebisdimethylamines, 400 Vinyl ketones, 71 Vinyllithium, 456 Vinylmagnesium halides, 91 Vinyl triphenylphosphonium bromide, 456-457... 

Synthesis of dienes [1, 169, before references], Tetrahydrofurane solutions of vinylmagnesium halides are readily accessible from vinyl halides by the method of Normant.19 Kauffmann and Sahm20 found that when a THF solution of the vinyl-magnesium compound (1) is treated at —60° to —40° under nitrogen with a suspension of cuprous chloride an intensely green or red solution is obtained which presumably contains a vinylcopper compound. When the mixture is warmed to... 

Unsaturated organomagnesium-halide reagents with Mg directly attached to an olefinic carbon—a substituted vinylmagnesium halide—are formed less easily than their... 

Cyclic vinylmagnesium halides react similarly, but in lower yield Isomerism around the double bond (E-Z) may be partly lost in the formation of the reagent once formed, they are configurationally stable. Occasionally, rearrangements are encountered in polyunsaturated systems, e.g. ... 

Nickel salts catalyze the cis-trans isomerization of vinylmagnesium halides . In the presence of a small amount of (Ph3P)2NiCl2, NiCl2 or (PPhj), either the cis- or the trans-organomagnesium-halide reagent in Eq. (1) is converted in 5 h at Rt to an equilibrium mixture ... 

Tetrahydrophthalides. The I esters is rendered regioselective bs the combination of the alkoxymagne Homologation-condensation. vinylmagnesium halide also triggen Bridged ring compounds can be prej... 

Homologation-condensation. The reaction of cyclic p-keto esters with a vinylmagnesium halide also triggers oxy-Cope rearrangement and Claisen condensation. Bridged ring compounds can be prepared by this method. ... 

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