Halide abstractor

Thus, in the presence of macrocycles, trialkylaluminum and even diorganozinc compounds have been used as alkide and halide abstractors to generate macrocycle-chelated organozinc cations (Scheme 45).108,109... 

The approach involves the reaction of a mid-valent metal halide with a mixture of arene, aluminium chloride (Lewis acidic halide abstractor) and aluminium powder (mild reductant). The charge on the resulting bis(arene) sandwich (n+) is generally dictated by the nature of the metal and EAN requirements, although once isolated, further reduction may be possible with stronger reductants. The approach can also be applied... 

Electron deficient coordinatively unsaturated thiaarsoli-dinium cations (50) and (51) have also been isolated. These carbenic arsenium cations have been prepared by the combination of the appropriate chlorodithiaarsolidine complex and a Lewis acid such as AICI3 or GaCb that function as a halide abstractor. The reaction can be carried out in CH2CI2 as the solvent (Scheme 2). 

As discussed earher, the electronically and coordinatively unsaturated cations [IndNi(PR3)]+, which are generated from the corresponding Ni-X precursors in the presence of excess MAO or other halide abstractors such as AgBp4, promote exclusively the dimerization of ethylene. The 1-butene... 

Recently, RajanBabu and co-workers successfully realized the enantioselective syntheses of biologically relevant molecules such as pseudopterosin G-J (Scheme 9.10) and indole alkaloids cis-trikentrin A and B (Scheme 9.11) by using Ni-catalyzed asymmetric hydrovinylation reaction as the key step. The utilization of binaphthol phosphoramidite (S,l a) L15 as the chiral ligand, in combination with NaBARF as the halide abstractor, was critical to achieve high regio- and enantioselectivity under very mild reaction conditions. ... 

Since VDF is a very reactive monomer, successful rt initiators should provide highly reactive, destabilized alkyl, semifluorinated, or perfluoroalkyl radicals. Thus, the visible light generated LnMt metal radical species should be a very good halide abstractor, and, for possible catalyzed CRP, L Mt-X should also be a very good halide donor. 

The respective Rh complex 21 (X = Cl) can be obtained without addition of halide abstractors [26]. 

Reactions of the new NHCP ruthenium alkylidene complexes 57 and 58a-f toward halide abstractors and application ofthe formed cationic species in ROMP catalysis will be published in due course. Additionally, the preparation of the corresponding JV-phosphino-NHC systems is also under way. 

Figure 15.8 Enantioselectivity versus nuclearity of the gold complexes employed. Ag-para-nitrobenzoate was used as the halide abstractor [68].

Following former synthetic approaches, halide complexes have continued to be used as suitable precursors for the activation of terminal alkynes. The generation of a free coordination site on the metal can be easily achieved upon treatment with a halide abstractor (sodium or silver salts). Following this synthetic approach, the following novel monosubstituted cationic vinylidenes have been synthesized ... 

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