Mild and Practical Reductions of Prochiral Ketones to Chiral Alcohols Using the Chiral Boronic Ester TarB-H

Abstract

Chiral alcohols are prepared under mild conditions in high enantiomeric excesses using the tartaric acid derived chiral boronic ester TarB-H. The phenylboronic acid was quantitatively recovered and recycled using a simple extraction with sodium hydroxide and diethyl ether. Aromatic and aliphatic secondary alcohols were prepared in up to 99% ee.

Key words

boron - reductions - asymmetric synthesis - chiral alcohols

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11

Phenylboronic acid costs approximately $430/mol and 3-nitrophenylboronic acid $1600/mol.