Plumbyls metal

Germyl, Stannyl, and Plumbyl Anions The preparative methods for the synthesis of the germyl, stannyl, and plumbyl anions are essentially the same as those mentioned above for the silyl anions. The most widely used methods are (1) reduction of halides R3EX (R = alkyl, aryl E = Ge, Sn, Pb X = Cl, Br) with alkali metals and (2) reductive cleavage of the E-E bond of R3E-ER3 (R = alkyl, aryl E = Ge, Sn, Pb) with alkali metals or organolithium reagents. Due to the favorable polarization of the (E = Ge, Sn, Pb) bond, the direct metalation... 

Nucleophilic cleavage of the lead-lead bond is one of the few ways to form plumbyl anions (equations 30, 37 and 38)45,51,52, but in the case of a sterically hindered and thus weak lead-lead bond, a metal-metal cleavage is required (equation 39)45,51-53. 

Alkaline and alkaline earth metal-14 compounds TABLE 4. Representative metaUated plumbyl compounds... 

The use of heavy metal reagents in the olefination of carbonyl compounds is in its infancy. However. Kauffmann and co-workers have shown that the phenyl-thio(triphenyl-stannyl or -plumbyl)methyl-lithiums (170) react with benz-aldehyde to give mixtures of threo- (171) and erythro- adducts (173). After the isomers are separated, each is capable of being converted into the ( )- or (Z)-p-phenylthiostyrene, (172) or (174), respectively, stereospecifically, as shown in Scheme 23. 

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