133520-54-4Relevant articles and documents
Enantioselective bio-hydrolysis of various racemic and meso aromatic epoxides using the recombinant epoxide hydrolase Kau2
Zhao, Wei,Kotik, Michael,Iacazio, Gilles,Archelas, Alain
, p. 1895 - 1908 (2015/06/02)
Abstract Epoxide hydrolase Kau2 overexpressed in Escherichia coli RE3 has been tested with ten different racemic and meso α,β-disubstituted aromatic epoxides. Some of the tested substrates were bi-functional, and most of them are very useful building blocks in synthetic chemistry applications. As a general trend Kau2 proved to be an extremely enantioselective biocatalyst, the diol products and remaining epoxides of the bioconversions being obtained - with two exceptions - in nearly enantiomerically pure form. Furthermore, the reaction times were usually very short (around 1 h, except when stilbene oxides were used), and the use of organic co-solvents was well tolerated, enabling very high substrate concentrations (up to 75 g/L) to be reached. Even extremely sterically demanding epoxides such as cis- and trans-stilbene oxides were transformed on a reasonable time scale. All reactions were successfully conducted on a 1 g preparative scale, generating diol- and epoxide-based chiral synthons with very high enantiomeric excesses and isolated yields close to the theoretical maximum. Thus we have here demonstrated the usefulness and versatility of lyophilized Escherichia coli cells expressing Kau2 epoxide hydrolase as a highly enantioselective biocatalyst for accessing very valuable optically pure aromatic epoxides and diols through kinetic resolution of racemates or desymmetrization of meso epoxides.
The acid accelerated ruthenium-catalysed dihydroxylation. Scope and limitations
Plietker, Bernd,Niggemann, Meike,Pollrich, Anja
, p. 1116 - 1124 (2007/10/03)
Recently, we discovered a significant rate acceleration in RuO 4-catalysed dihydroxylations of olefins by addition of Broensted-acids resulting in a reduction of the catalyst loading to only 0.5 mol%. The present paper gives a full account on the optimisation protocol that led to the discovery of the beneficial influence of protic acids. A strong focus is set on the detailed description of the influence of different reaction parameters on both reactivity and selectivity. In the second part an intense investigation of scope and limitations will be presented. The results provided in this manuscript might lead to a deeper understanding of competing processes that influence the selectivity in RuO4-catalysed dihydroxylations.
Synthesis of O-Protected (R)-2-Hydroxy Aldehyde and Their Hydrocyanation
Effenberger, Franz,Hopf, Martin,Ziegler, Thomas,Hudelmayer, Jochen
, p. 1651 - 1659 (2007/10/02)
The synthesis of O-silyl- and O-benzyl-protected (R)-2-hydroxy aldehydes (R)-6 from (R)-2-hydroxy carboxylic acids (R)-1 is described.While attempts for their diastereoselective hydrocyanation with hydrocyanic acid and (R)-oxynitrilase as catalyst have not been successful, the cyano silylation with trimethylsilyl cyanide occurred diastereoselectively with a ratio of 81:19 preferring the threo form without racemization at C-2 of the 2-hydroxy aldehyde. Key Words : (R)-2-Hydroxy aldehydes, O-protected / Hydrocyanation
