Alkyllead halides

Reductions of alkyllead halides with LiAlFLt are among the most successful ones and are, despite complications in some cases241, easy to perform. R3PbCl can easily be reduced in liquid ammonia by KBH4239 241 through an R3PbBH4 intermediate that is converted into the trialkyllead hydride by NH3 ... 

In the case of reductions by LiAlH4 the reaction conditions depend on the type of alkyllead halide used, R3PbX, R2PbX2 or RPbX3 ... 

An anionic active centre can be transformed to a radical centre by peroxy-alkyl halides [244] or by molecular oxygen [245], It appears, however, that the most elegant way so far was found by the British workers [246,247], They make use of the decomposition of unstable alkylsilver compounds generated from alkyllead salts and silver halides. The transformation thus proceeds in two steps. In the first step, a suitable Pb-containing end group is formed on the macroanion... 

A number of methods to increase the thermal stability of Kdbrich reagents have centered around replacement of the lithium counterion normally present with a variety of transition metals, chiefly titanium, hafnium and copper." For example, the reagent derived from transmetalladon of lithium dichlorometh-ane with titanium isopropoxide could be reacted with various ketones and aldehydes to afford halohydrin adducts in good yields at temperatures as high as 0 °C. Competition experiments established the chemoselectivity of this reagent (Scheme 14). The direct activation of severid allylic halides has been accomplished with tin and chromium ° reagents (equation 26). Transmetallation of an alkyllead precursor has also been noted. 

High yields of alkyllead compounds are obtained by reaction of alkyl halides with mixtures of lead and magnesium.478... 

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