Stannanes reactions with organometallic compounds

Organometallic compounds with a 3-butenyl moiety can produce cyclopropylmethyl derivatives via an addition of electrophiles to the terminal carbon atom of the double bond followed by the loss of the metallic group. 3-Butenylsilanes, -stannanes (equation 30 31,134 and -cobaltare the representative compounds. Thus, the reaction of... 

BF3-OEt2 reverses the usual anti selectivity observed in tbe reaction of crotyl organometallic compounds (based on Cu, Cd, Hg, Sn, Tl, Ti, Zr, and V, but not on Mg, Zn, or B) with aldehydes (eq la) and imines (eq lb), so that homoallyl alcohols and homoallylamines are formed, respectively. " The products show mainly syn diastereoselectivity. BF3-OEt2 is the only Lewis acid which produces hydroxy- rather than halo-tetrahydropyrans from the reaction of aUyl-stannanes with pyranosides. The BF3-OEt2 mediated condensations of y-oxygenated allylstannanes with aldehydes (eq Ic) and with activated imines (eq Id) affords vicinal diol derivatives and 1,2-amino alcohols, respectively, with syn diastereoselectivity. The activated imines are obtained from... 

The Pd-catalyzed cross-coupling reactions of metal nucleophiles with carbon electrophiles are of considerable value for the regio- and stereocontrolled synthesis of functionalized organometallic compounds, in particular, silanes, stannanes, and boianes, which are important reagents for Pd-catalyzed carbon-carbon CTOss-coupling as shown in Sects. III.2.2-in.2.4. Symmetrical bimetallic compounds such as disilanes, distannanes, and diborons are usually used as metal nucleophiles. The present metallation is applicable to aryl, benzyl, vinyl, acyl, and allyl (Sect. V.2.3.3) electrophiles. 

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