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Stereoselective Reduction of 2‐Hydroxy Ketones towards syn ‐ and anti ‐1,2‐Diols
Author(s) -
Husain Syed Masood,
Stillger Thomas,
Dünkelmann Pascal,
Lödige Melanie,
Walter Lydia,
Breitling Elke,
Pohl Martina,
Bürchner Mara,
Krossing Ingo,
Müller Michael,
Romano Diego,
Molinari Francesco
Publication year - 2011
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201100150
Subject(s) - chemistry , stereoselectivity , selectivity , borohydride , sodium borohydride , reagent , combinatorial chemistry , steric effects , biocatalysis , diol , chelation , catalysis , reducing agent , organic chemistry , ionic liquid
Stereoselective reduction of 2‐hydroxy ketones should in principle give access to syn ‐ and anti ‐1,2‐diols. anti ‐1,2‐Diols are accessible in a highly selective way using zinc borohydride [Zn(BH 4 ) 2 ] under chelation control ( dr >20:1). Diastereoselective reduction of unprotected or even protected 2‐hydroxy ketones towards syn ‐1,2‐diols could be achieved only with moderate selectivity of dr ≤5:1. Even when using sterically demanding protecting groups and/or polymer‐supported borohydride reagents high selectivity could not be achieved. A new ionic liquid‐dependent borohydride reduction method, although highly attractive with respect to reaction engineering, resulted in only moderate to good selectivity. An efficient two‐step biocatalytic method for the synthesis of syn ‐1,2‐diols is described. The method relies on the whole‐cell Pichia glucozyma ‐catalyzed stereoselective reduction of the unprotected ( R )‐2‐hydroxy ketones ( dr >10:1). The latter are accessible through thiamine diphosphate‐dependent enzyme‐catalyzed synthesis starting from simple aldehydes. Thus, biocatalytic transformations enable a process which is hardly accessible through present non‐enzymatic methods.