ChemInform Abstract: (R)-1,2,2-Triphenyl-2-(trimethylsiloxy)ethyl Propionate: anti- Selective and Diastereofacially Selective Aldol Addition; Diastereoselective Silylation and Alkylation.
Abstract
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ChemInform Abstract
Aldol reactions of zirconium enolate derived in situ from readily obtained chiral title reagent (IV) proceed with high simple diastereoselection (anti:syn) as well as high diastereofacial selectivity to provide the anti-adducts (VI) in good yield. These adducts can be efficiently converted into enantiopure carboxylic acids (cf. (VIII)) and diols (cf. (IX)) thus demonstrating the synthetic potential of stereoselective aldol reaction induced by the chiral auxiliary triphenylglycol (I). Surprisingly, an exclusive diastereoselective carbon silylation occurs upon treatment of deprotonated ester (IV) with Tms-Cl. On the other hand, alkylation of the deprotonated ester (IV) with primary alkyl halides provides α -branched esters with moderate to acceptable diastereoselectivity (cf. (XIII)/(XIV)).
