Palladium isocyanides

Stone et al. 43, 60, 61) have studied reactions of nickel and palladium isocyanides and a number of fluorocarbons which give a remarkable variety of products. With Ni(CNBu )4 and fluoroolefins [C2F4, (CF3)2C=C(CN)2 and CF2 = CFCF = CF2] themetallocyclic complexes (XXXIV), (XXXV), and (XXXVI) are observed 60,61) the complex Ni(CNBu )2(CjF5), analo-... 

A large amount of the work on palladium isocyanide complexes has been mentioned earlier, in discussions on insertion reactions 30,74,108,169,170) and on addition reactions of coordinated isocyanides 25, 33, 34, 49) the reactions of [Pd(CNBu )2] with oxygen 107) and with various olefins 29, 110) were noted. 

A unique bis-silylation system, in which a bis(silyl)palladium intermediate is generated via recombination of two Si-Si bonds, has been developed.8,97 A bis(disilanyl)dithiane reacts with alkynes in the presence of a palladium/ isocyanide catalyst, giving five-membered ring bis-silylation products in high yield with elimination of hexamethyl-disilane (Scheme 14). The recombination, that is, bond metathesis, is so efficient that no product derived from direct insertion of acetylene into the Si-Si bonds of the bis(silyl)dithiane is formed at all. 

Palladium-catalyzed bis-silylation of benzynes has been achieved. Reaction of 2-trimethylsilylaryl triflates with cyclic disilanes in the presence of KF/18-crown-6 affords cyclic bis-silylation products in good yields (Equation (29)). It is crucially important to use the palladium-isocyanide catalyst.99 100... 

Bis-silylation of bicyclopropylidene in the presence of the palladium-isocyanide catalyst with hexamethyldisilane and phenylpentamethyldisilane gives 1,2-addition products in good yields at 70 °C vide supra). No G-G bond cleavage takes place with the bis-silylation reaction. In contrast to this example, in which both the cyclopropane rings are... 

A tetragermylethene derivative has been synthesized through intramolecular digermation using the palladium-isocyanide catalyst under high pressure (5 kbar).95... 

Addition of distannane to alkenes has been achieved only with strained cyclopropenes (Equation (60)).158 3,3-Disubstituted cyclopropenes undergo highly face-selective distannation in the presence of the palladium-isocyanide complex to afford m-adducts. 

The palladium-isocyanide complex is effective for silastannation of ethoxyethyne, a labile alkyne, to produce (Z)-1-ethoxy-l-silyl-2-stannylethene with high regioselectivity (Equation (106)).253 The regioselectivity observed has also been studied by computation.263... 

The palladium-isocyanide catalyst is also effective for the silastannation of cyclopropenes (Equation (115)).158 The reaction proceeds smoothly under mild conditions (RT, 10-30 min) with high face selectivity to give tetrasubstituted... 

Acyclic carbenes, with palladium isocyanides, 8, 258 Acyclic diene metathesis polymerization alkynes, 1, 191 characteristics, 1, 138 in ionic liquids, 1, 869... 

Palladium isocyanide complexes react with amines and alcohols to give palladium Carbene Complexes (equation 15) in a reaction that is a nucleophihc attack on the isonitrile carbon. These complexes easily lose a halide if it is trans to the carbene hgand, since the carbene carbon has a high trans influence. The structures of these compounds have the carbene carbon and its two heteroatom groups in one plane, which is perpendicular to the coordination plane of the Pd. 

For stereoselective intramolecular bis-silylation of alkenes promoted by a palladium-isocyanide catalyst see reference 32. 

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