126060-73-9Relevant articles and documents
Catalytic Asymmetric Epoxidation of Aldehydes with Two VANOL-Derived Chiral Borate Catalysts
Gupta, Anil K.,Yin, Xiaopeng,Mukherjee, Munmun,Desai, Aman A.,Mohammadlou, Aliakbar,Jurewicz, Kelsee,Wulff, William D.
supporting information, p. 3361 - 3367 (2019/02/16)
A highly diastereo- and enantioselective method for the epoxidation of aldehydes with α-diazoacetamides has been developed with two different borate ester catalysts of VANOL. Both catalytic systems are general for aromatic, aliphatic, and acetylenic aldehydes, giving high yields and inductions for nearly all cases. One borate ester catalyst has two molecules of VANOL and the other only one VANOL. Catalysts generated from BINOL and VAPOL are ineffective catalysts. An application is shown for access to the side-chain of taxol.
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.
Metal-free ring-opening of epoxides with potassium trifluoroborates
Roscales, Silvia,Csaky, Aurelio G.
supporting information, p. 454 - 456 (2014/01/06)
The ring-opening of epoxides with potassium trifluoroborates proceeds smoothly in the presence of trifluoroacetic anhydride under metal-free conditions. The reactions are regioselective and afford a single diastereomer. Both electron-rich and electron-poor aryltrifluoroborates are tolerated.
