creators_name: Pal, Mohan
creators_name: Srivastava, Gautam
creators_name: Sharma, Amar Nath
creators_name: Kaur, Suneet
creators_name: Jolly, R S
type: article
datestamp: 2016-01-29 07:50:30
lastmod: 2016-01-29 07:50:30
metadata_visibility: show
title: Biocatalyzed asymmetric reduction of benzils to either benzoins or hydrobenzoins: pH dependent switch
ispublished: pub
subjects: QR
note: Copyright of this article belongs to RSC.
abstract: Enantiopure benzoins and hydrobenzoins are precursors of various pharmaceuticals and biologically active compounds. In addition, hydrobenzoins are precursors of chiral ligands and auxiliaries in stereoselective organic synthesis. Biocatalytic reduction of benzils is a straightforward approach to prepare these molecules. However, known methods are not selective and lead to formation of a mixture of benzoin and hydrobenzoin, requiring expensive separation procedures. Here, we describe an enzyme system Talaromyces flavus, which exhibited excellent pH dependent selectivity for the conversion of benzil to either benzoin or hydrobenzion in high ee. Thus, (S)-benzoin was the exclusive product at pH 5.0 (ee >99%), whereas at pH 7.0, (S,S)-hydrobenzoin (ee >99%, dl/meso 97:3) was the exclusive product. The observed pH dependent selectivity was shown to be due to the presence of multiple enzymes in Talaromyces flavus, which specifically accepted either benzil or benzoin as a substrate and exhibited different pH profiles of their activity. The biocatalyst efficiently reduced a variety of symmetrical and unsymmetrical benzils. Moreover, a 36.4 kDa benzoin reductase was purified, the N-terminal sequence of which did not show a significant similarity to any of the known reductase/dehydrogenase in the database. The protein therefore appears to be a novel reductase.
date: 2015
date_type: published
publication: Catal. Sci. Technol.
volume: 5
number: 8
publisher: Royal Society of Chemistry
pagerange: 4017-4028
id_number: doi:10.1039/C5CY00158G
refereed: TRUE
issn: 2044-4753
official_url: http://dx.doi.org/10.1039/C5CY00158G
citation:   Pal, Mohan and Srivastava, Gautam and Sharma, Amar Nath and Kaur, Suneet and Jolly, R S  (2015) Biocatalyzed asymmetric reduction of benzils to either benzoins or hydrobenzoins: pH dependent switch.  Catal. Sci. Technol., 5 (8).  pp. 4017-4028.  ISSN 2044-4753