Copper methyl -alkoxides

Previously published methods for the synthesis of dimethylzinc, a useful alkylating agent, include the reaction of dimethylmercury with metallic zinc,1 the reaction of a zinc-copper couple with methyl iodide,2 and the Grignard method.3 The reaction of trimethylaluminum with zinc(II) halides or alkoxides can be used,4 but it is more convenient to use zinc(ll) acetate, which is very readily obtained by dehydrating the commercial dihydrate with boiling acetic anhydride or by the reaction5 ... 

Atom transfer radical polymerization (ATRP) and nitroxide-mediated (107-109) polymerization both show promise in terms of the ability to fine-time polymer architecture using living radical methods. ATRP has been snccessfiilly used in the polymerization of methyl methylacrylate using copper (110), rnthe-nium/aluminum alkoxide (111), iron (112), and nickel (113) catalyst systems. 

The similar alkoxide- or hydroxide-induced trifluoromethylation was also found to work with other electrophiles. Diphenyl disulfide can be trifluoromethylated to give trifluoromethyl phenyl sulfide in 87% yield (eq 4). Methyl benzoate can be trifluoromethylated to generate 2,2,2-trifluoroacetophenone in 30% yield at temperatures between —50°C and —20°C. Trifluo-romethylcopper (CF3CU) can be generated in situ with trifluoromethyl sulfone, f-BuOK, and copper iodide (Cul), and it then further reacts with iodobenzene at 80 °C for 20 h to give a,a,a-trifluorotoluene in 26% 3neld. ... 

While ATRP of methyl acrylate was reported only for the copper catalyst system [290-292] methyl meth(acrylate) was also polymerized with copper [290,293 295], ruthenium/aluminum alkoxide [296,297], iron [298,299] and nickel [300 303] eatalyst systems (Table 9). Thereby, it must be noted that in principle, the ruthenium-based system proposed by Sawamoto et al. requires the addition of Lewis acids, e.g., Al(0- -Pr)3 [297]. Recent investigations showed, that the half-metallocene -type ruthenium(II) chloride Ru(Ind)Cl(PPh3)2 (Ind = indenyl) led to a fast and well controlled polymerization even without the addition of Al(0- -Pr)3, whereas in case of a polymerization with Ru(Cp)Cl(PPh3)2 (Cp = cyclopentadienyl), the addition of Al(0-z-Pr)3 is necessary. The activity of Ru(II)-catalysts decreases in the order Ru(Ind)Cl(PPh3)2 > RuCl2(PPh3)2 > Ru(Cp)Cl(PPh3)2 [304]. 

The 1,2-adducts (32) of 2-litho-l,3-dithians and cyclohex-2-enone can be isomerized to the more stable 1,4-adducts (33) by conversion into the potassium alkoxides (but not the less dissociated sodium or lithium salts).Direct formation of enone 1,4-adducts occurs when HMPA-THF is used as the solvent, and enolate trapping can be effected when the initial enone 1,4-adduct is treated with methyl iodide.The allylic anion derived from (34) undergoes cr-1,4-addition to cyclohexenone in the presence of Cul (Scheme 2). In the absence of the copper salt, both y-1,4- and cr-1,4-addition occur, with the former predominating. In contrast, allylation of (34) in the presence of Cul occurs primarily at the y-position, while cr-allylation is observed otherwise.The lithio-anion of 2-(yff-styryl)-... 

In addition to the methods described above, prenol (51) can be prepared from methyl-butynol (43) by rearrangement to prenal (52) using a titanium alkoxide/copper chloride catalyst [69, 70] followed by selective hydrogenation using a ruthenium rhodium tris( 7-sulfonatoyl)phosphine trisodium salt (TPPTS) catalyst [71, 72]. However, it is more usual to prepare the prenyl esters by nucleophilic substitution of a carboxylate anion on prenyl chloride [503-60-6] (56) which, in turn, is available through hydrochlorination of isoprene [78-79-5] (1). This hydrochlorination often employs copper ions as catalysts. These processes are shown in Fig. 8.14. 

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