Magnesiums stannyl

C4H9Br2ClMgSn Magnesium Dibrom-(trimethyl-stannyl)-methyl- -chlorid XIII/2a, 165f. 

A related approach to 1,1-dimetallated compounds relies on the allylation of 1-alkenyl-magnesium, -lithium, and - uminum derivatives (23) with allylzinc bromides (22), which proceeds readily at 35 C (Scheme 7 Table 4). The resulting gem-dimetallic intermediates can be trapped by protonation (24 26,25 - 29), stannylation (24 - 27) or, more interestingly, with aldehydes in the presence of BFs OEt (e.g. 24a - 28). The dimetallated species (24) were also trapped with alkylidene malonates, l2/H30, ... 

Before lithium aluminium hydride was available as a reducing agent, the tin hydrides were prepared by treating the stannyl-lithium or stannyl-sodium compounds with ammonium halides in liquid ammonia.31 More recently, stannyl-magnesium compounds have been used in the same way (equation 15-14).32... 

Traditionally, aldol reactions were carried out under protic conditions, such that the enolate was formed reversibly (see Volume 2, Chapter 1.5). An added measure of control is possible if one uses a sufficiently strong base that the enolate may be quantitatively formed prior to addition of the electrophile. The renaissance that has occurred in the aldol reaction in the last two decades has been mainly due to the development of methods for the formation and use of preformed enolates. The simplest enolates to prepare are those associated with lithium and magnesium, and there now exists a considerable literature documenting certain aspects of lithium and magnesium enolate aldol chemistry. This chapter summarizes the aldol chemistry of preformed enolates of these Group I and Group II metals. Other chapters in this volume deal with boron enolates, zinc enolates, transition metal enolates and the related chemistry of silyl and stannyl enol ethers. 

Chloro(trimethylplumbyl)magnesium, Pb-00013 51275-77-5 Tris[bis(trimethylsilyl)methyl]stannyl, Sn-00364... 

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