Metalating reagent

The pyrometaHurgical processes, ie, furnace-kettle refining, are based on (/) the higher oxidation potentials of the impurities such as antimony, arsenic, and tin, ia comparison to that of lead and (2) the formation of iasoluble iatermetaUic compounds by reaction of metallic reagents such as 2iac with the impurities, gold, silver and copper, and calcium and magnesium with bismuth (Fig. 12). 

Yields are best in the case of aromatic metallic reagents. Use of aUphatic reagents favors low molecular weight products. Products often are recovered by water addition, followed by separation and distillation of the organic layer. Such procedures inevitably lead to acidic by-products when there is incomplete replacement of the halogens on phosphoms. A modification of the Wurt2 reaction sometimes is used. 

A. A. Morton, Solid Organoalkali Metal Reagents, Gordon Breach, New York, 1964. 

Mixed-Metal Systems. Mixed-metal systems, where a zirconium alkyl is formed and the alkyl group transferred to another metal, are a new apphcation of the hydrozirconation reaction. These systems offer the advantages of the easy formation of the Zr—alkyl as well as the versatiUty of alkyl—metal reagents. For example, Cp2ZrRCl (R = alkyl or alkenyl) reacts with AICI3 to give an Al—alkyl species which may then be acylated with... 

Synthesis of heterocycles by iodocarbocyclization and iodoaminocyclization with metal reagent participation 99SL1191. 

Nishiyama H., Motoyama Y. Other Transition Metal Reagents Chiral Transition-Metal Lewis Acid Catalysis for Asymmetric Organic Synthesis in Lewis Acid Reagents 1999 225, Ed Yamamoto H., Pb. Oxford Univ. Press, Oxford Keywords asymmetric Diels-Alder reactions, chiral transition metal Lewis-acid catalysis, asymmetric synthesis... 

For lists of reagents, with references, see Ref. 568, p. 31. For a review with respect to transition metal reagents, see Luh, T. Ni, Z. Synthesis, 1990, 89. For some very efficient nickel-containing reagents, see Becker, S. Fort, Y Vanderesse, R. Caubere, P. / Org. Chem., 1989, 54, 4848. 

By this method, different classes of PNs were prepared by replacing chlorine atoms of the polydichlorophosphazene intermediate by primary or secondary amines, alkoxide or aryl-oxide, or organ metallic reagents. " ... 

Addition of crotyl metal reagents to 4-acetoxy-l,3-dioxanes was utilized in the synthesis of dipropionate synthons [52] (Scheme 22). These reactions... 

Richmond TG (1999) Metal Reagents for Activation and Functionalization of Carbon-Fluorine Bonds. 3 243-269... 

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