Alkenes, metal catalyzed halides

Transition metal-catalyzed transformations are of major importance in synthetic organic chemistry [1], This reflects also the increasing number of domino processes starting with such a reaction. In particular, Pd-catalyzed domino transformations have seen an astounding development over the past years with the Heck reaction [2] - the Pd-catalyzed transformation of aryl halides or triflates as well as of alkenyl halides or triflates with alkenes or alkynes - being used most often. This has been combined with another Heck reaction or a cross-coupling reaction [3] such as Suzuki, Stille, and Sonogashira reactions. Moreover, several examples have been published with a Tsuji-Trost reaction [lb, 4], a carbonylation, a pericyclic or an aldol reaction as the second step. 

Although most of the reports that have appeared since 1980 on hydroformylation of alkenes focus on rhodium catalysts, alkene hydroformylation catalyzed by Ptn complexes in the presence of Sn11 halides has been the object of great interest and platinum can be considered as the second metal in hydroformylation.77-79... 

Thus far, enantioselective intramolecular aziridination via metal nitrene intermediates has not been successful. Bromamine-T has recently been shown to be a viable source of nitrene for addition to alkenes in copper halide catalyzed reactions, " and so has iodosylbenzene (Phl=0) that forms 44 in situ. Conceptually, aziridination does not necessarily fall between cyclopropanation and epoxidation, as some have suggested. Instead, metal nitrene chemistry has unique problems and potential advantages associated with the electron pair at nitrogen that are yet to be fully overcome. 

Braese, S. de Meijere, A. Gross-Coupling of Organic Halides with Alkenes the Heck Reaction. In Metal-Catalyzed Cross-Coupling Reactions, 2nd ed. de Meijere, A., Diederich, F., Eds. Wiley-VCH Weinheim, 2004 pp 217-315. 

Carbocations formed through protonation of alkenes by proton acids are usually assumed as intermediates in alkylation with alkenes. Metal halides, when free of protic impurities, do not catalyze alkylation with alkenes except when a cocatalyst is present. It was shown that no neat conjugate Friedel-Crafts acids such as HA1C14 or HBF4 are formed from 1 1 molar compositions in the absence of excess HC1 or HF, or another proton acceptor.163-166 In the presence of a proton acceptor (alkene), however, the Lewis acid halides—hydrogen halide systems are readily able to generate carbocations ... 

Brase, S. and de Meijre, A., Palladium-catalyzed Coupling of Organyl Halides to Alkenes - the Heck Reaction , in Metal-catalyzed Cross-coupling Reactions, Wiley-VCH, Weinheim, 1998, pp. 99-166. 

S. Brase and A. de Meijere, Palladium-Catalyzed Coupling of Organyl Halides to Alkenes—The Heck Reaction, in Metal-Catalyzed Cross-Coupling Reactions, (F. Diederich, P. J. Stang, Eds.), Wiley-VCH, Weinheim, 1998, 99-154. 

The nitrogen source for the aziridination of alkenes, a nitrene or nitrenoid, can be generated in various ways (1) oxidation of a primary amine (2) base-induced -elimination of HX from an amine or amide with an electronegative atom X (X = halogen, O) attached to the NH group or by -elimination of metal halides from metal A-arenesulfonyl-A-haloamides (3) metal-catalyzed reaction of [A-(alkane/arenesulfonyl)imino]aryliodanes (4) thermolytic or photolytic decomposition of organyl azides and (5) thermally induced cycloreversion reactions . 

Brase S, de Meijere A (2004) Cross-coupling of organyl halides with alkenes the Heck reaction. In de Meijere A, Diederich F (eds) Metal-catalyzed cross-coupling reactions. Wiley, Weinheim, p 217... 

Brase, S., De Meijere, A. Palladium-catalyzed coupling of organyl halides to alkenes - the Heck reaction, in Metal-Catalyzed Cross-... 

The discovery of Minisci et al.,39 Asscher and Vofsi,40 and others41 of the transition metal catalyzed addition of haloalkanes to alkenes by a redox chain process (Scheme 14) has found vast synthetic applications.830,89 A recent summary has been given by van Koten et al.90 Virtually any olefin can serve as the source of reactive unsaturation, and a variety of polyhalogenated compounds such as alkyl halides,... 

What is fhe implication of our work wifh respect to the metal-catalyzed polymerization of polar vinyl monomers FirsL for fhe late metal compounds, fhe polar vinyl monomers can clearly outcompete efhene and simple 1-alkenes wifh respect to insertion. However, fhe ground-state destabilization of the alkene complex that favors the migratory insertion of fhe polar vinyl monomers is a two-edged sword because it biases the alkene coordination towards ethene and l-alkenes. Indeed, we have observed fhe near quantitative displacement of vinyl bromide by propene to form 7 from 3 (Scheme 9.1). Thus, the extent of incorporation of fhe polar vinyl monomer in fhe polymer will depend on the opposing trends in alkene coordination and migratory insertion. The above discussion does not take into account the problem of functional group coordination for acrylates or halide abstraction for vinyl hahdes. 

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