Regioselective Carboxylation of Silicon-Stabilized Allylic Carbanions and the Synthetic Utility of 2-Silyl-3-butenoates
Carbanions of allylic dimethylphenylsilanes show remarkable regioselectivity toward carboxylation with carbon dioxide and methylation with methyl iodide.Methylationn of these compounds occurred preferentially at α position, although allyltrimethylsilane and allyltriphenylsilane are known to give γ selectivity toward the same electrophiles.Moreover, their aluminum "ate" complexes react with carbon dioxide regioselectively at the α position irrespective of methyl substitution pattern of the allylic moieties.The α-carboxylated allylic silanes proved to be useful synthons of 3-(methoxycarbonyl)allyl anions after esterifiaction.
Uno, Hidemitsu
p. 2471 - 2480
(2007/10/02)
NEW SYNTHESIS OF METHYL 2-TRIORGANOSILYL-3-BUTENOATES AS A NEW SYNTHON OF 3-METHOXYCARBONYLALLYL ANION
Methyl 2-triorganosilyl-3-butenoates, which are selectively obtained from the carboxylation of the corresponding allylsilanes via allylic aluminates, react with various kinds of electrophiles to give γ substituted (E)-α,β-unsaturated esters in highly regio- and stereoselective manner with the aid of a Lewis acid.