Asymmetric reduction of aliphatic ketones and acyl silanes using chiral anti-pentane-2,4-diol and a catalytic amount of 2,4-dinitrobenzenesulfonic acid

Abstract

Abstract-Aliphatic ketones were reduced to the corresponding secondary alcohols by using anti-1,3-diol and a catalytic amount of 2,4-dinitrobenzenesulfonic acid (DNBSA) in benzene at reflux. Addition of 1-octanethiol in that media improved the efficiency of the reduction. Asymmetric reduction of aliphatic ketones was performed by using chiral anti-pentane-2,4-diol, and highly asymmetric induction (up to >99% ee) was observed in the reduction of tert-alkyl ketones. Asymmetric reduction of acyl silanes using chiral antipentane-2,4-diol and DNBSA proceeded efficiently in the absence of octanethiol and the corresponding -silyl alcohols were obtained in high yields with high ees.

Synthetic methods Part (II): oxidation and reduction methods

“…Two significant reports from the Matsuo group concern ketone reduction by 1,3-diols in the presence of catalytic 2,4-dinitrobenzenesulfonic acid. 225,226 This methodology arose from a serendipitous observation of ketone reduction as opposed to the expected ketal formation. The group have shown that enantioinduction up to 99% e.e.…”

Reaction Engineering of Biocatalytic Enantioselective Reduction: A Case Study for Aliphatic Ketones

“…In this work we focused on the enantioselective reduction of aliphatic ketones into their corresponding alcohols using oxidoreductases, since there is no chemical alternative available that yields similar enantiomeric excess (ee). − Long-chain enantiopure aliphatic alcohols are an interesting raw material in the pharmaceutical industry. They have also been used for the production of liquid crystals with interesting optical properties …”

Benzoyl trimethylsilane

“…entry 2) 16. A mixture of Ti(O-iPr)4 /Et 2 Zn resulted in the isolation of the racemic 16 in good yield 17.…”