Enantioselective Synthesis of α-Tertiary Hydroxyaldehydes by Palladium-Catalyzed Asymmetric Allylic Alkylation of Enolates
作者:Barry M. Trost、Jiayi Xu、Markus Reichle
DOI:10.1021/ja067342a
日期:2007.1.1
Chiral alpha-tertiary hydroxyaldehydes are very versatile building blocks in synthetic chemistry. Herein, we report the first examples of a catalytic asymmetric protocol for the synthesis of such compounds from readily available alpha-halo or alpha-hydroxy ketones or enol silyl ethers with excellent yields and nantioselectivity. Its synthetic utility is demonstrated in the short, efficient formal synthesis of (S)-oxybutynin. In this process, the chiral ligand controls the regioselectivity as well as the enantioselectivity.
Enantioselective synthesis of 2-allyl and 2-(3-trimethylsilylpropargyl)-2-hydroxycyclohexanone using osmium-catalyzed asymmetric dihydroxylation
The catalytic asymmetric dihydroxylation of (1-cyclohexenyl) or (1-cyclopentenyl) acetonitrile 5 and 15 with AD-mix-beta occurred with good enantiofacial selectivity (87 to 94.7% ee after recrystallization) giving (R,R)-diols in agreement with the mnemonic device. The 6-membered ring diol nitrile was easily transformed, via standard functional group manipulations, to 2-allyl and 2-(3-trimethylsilylprop-2-ynyl)-2-hydroxycyclohexanone in about 35% overall yield. (C) 1998 Elsevier Science Ltd. All rights reserved.