Coupling with alkenes

Aiyl diazonium salts can be used coupled with alkenes in a Heck-like reaction (14-20). Other reactive aryl species also couple with aryldiazonium salts in the... 

Alkenyl trifluoromethanesulphonates (enol triflates) undergo Heck coupling with alkenes efficiently (equation 123)209a 215. This reaction is a useful variation of the use of vinyl halides not only because they are easy to prepare from the corresponding carbonyl compounds, but also because yields are good, and the stereochemistry of the triflate is largely maintained. 

The cycloaddition reactions of isoquinolinium species produce fused isoquinoline products. The Af-ylide of 53, formed with base addition, couples with alkenes <99S51> or imines <99T7279> to afford tricyclic products, such as 54. Pyrrole-fused isoquinolines result from the reaction between mUnchnone imine intermediates and a,yff-ethylenic esters <99EJOC297>. N-Arylimides undergo 1,3-dipolar cycloaddition with strained frani-cyclooctenes, as opposed to common cycloalkenes, to tdford the pyrazolidine-fused ring system <99H(50)353>. 

Five-membered ring closures have been observed when o-halostyrene derivatives such as 113 were coupled with alkenes under palladium catalysis. Apparently, an intramolecular carbopalladation with S-exo-trig ring closure to give 114-R can favorably compete with / -hydride elimination in the first-formed intermediate to yield 115-R This reaction mode for the halostyrene is observed especially under Jeffery conditions, when the alkene is ethene or propene (Scheme 31). Under the same conditions, however, < -dibromobenzene gives very high yields of o-dialkenylbenzene derivatives (see Scheme 2). ... 

Coupling with alkenes and alkynes.2 The reagent reacts with these substrates to form metallacyclic compounds, which are hydrolyzed to acyclic compounds. The adducts are formed with high regioselectivity. 

Cross-coupling with alkenes (carbometallation of alkenes)... 

Cross-coupling with Alkenes (Carbometallation of Alkenes)... 

Oxidative cross-coupling with alkenes is possible with Pd(OAc)2 [109], The reaction proceeds by the palladation of benzene to form phenylpalladium acetate (164), followed by alkene insertion and elimination of /1-hydrogen. Heteroaromatics such as furan and thiophene react more easily than benzene [109]. Stilbene (177) is formed by the reaction of benzene and styrene. The complex skeleton of paraberquamide 179 was obtained in 80% yield by the Pd(II)-promoted coupling of the indole ring with the double bond in 178, followed by reduction of the intermediate with NaBELt [110]. 

A haloalkene that contains a stereogenic C=C double bond can usually be coupled with alkenes via the Heck reaction without isomerization. This is illustrated with the three reaction pairs in Figure 16.36. As can be seen, both the as- and the /raw-configured iodoalkenes react with acrolein or methyl vinyl ketone or acrylic acid methyl ester with complete retention of the C=C double bond configuration. These coupling reactions are thus stereoselective and— when considered as a pair—stereospecific. 

The R- radicals can also undergo cross coupling with alkenes and with hetero-arenes.2... 

Furthermore, Pd-catalyzed aminations can be sequentially coupled with alkene insertion and amination. Wolfe and Lira [102] have established a transformation involving two different sequential metal-catalyzed reactions that lead to AT-aryl-2-benzylindolines 125 in moderate to excellent yields upon formation of two C - N bonds and one C - C bond in a one-pot process (Scheme 45). Interestingly, the selective installation of two different aryl groups in this sequence can be accomplished by in situ modification of the Pd catalyst system Pd-126 upon addition of the chelating ligand dpephos prior to addition of the second aryl bromide (Scheme 46). The selectively substituted indoline derivatives 127 were isolated in good to excellent yields. 

Triorganosilyl(dizincio)methanes c Pd-catalyzed couplings with alken 3-silyl-l,5-dienes. ... 

Cyclopropyl trimethylsilyl ethers, which were readily prepared from aldehydes, ketones and esters, coupled with alkenes on treatment with mercury(II) acetate and, after reduetion with sodium borohydride, afforded chain-extended carbonyl compounds, e.g. 37, in moderate to good yields. The whole reaction could be carried out in one pot. 

Milstein and co-workers were the first to introduce catalysts capable of activating various aryl chlorides in 1992 [175]. By using palladium complexes of highly basic and sterically demanding chelating bisphosphines, for example, dippb [l,4-bis(di-isopropylphosphinyl) butane], even chlorobenzene was coupled with alkenes in high yields (Table 1, 70-95% yield TON = 70-95) [175]. However, these catalysts are extremely sensitive to air. Herrmann, Beller, and co-workers introduced more robust palladacycles [cyclopalladated... 

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