performance of highly efficient aliphaticamines racemization, under mild conditions at 30 °C. The reaction proceeds via the reversible generation of prochiral α-aminoalkyl radicals. The latter may result either from a redox process between the thiyl radical and the amine or from direct hydrogen atom abstraction by thiyl radical. As hydrogen atom donor, the thiol plays a crucial role. While the racemization
Chemoenzymatic Dynamic Kinetic Resolution of Primary Amines Catalyzed by CAL-B at 38–40 °C
作者:Florent Poulhès、Nicolas Vanthuyne、Michèle P. Bertrand、Stéphane Gastaldi、Gérard Gil
DOI:10.1021/jo201256w
日期:2011.9.2
The (R)-selective chemoenzymatic dynamic kinetic resolution of primary amines was performed at 38-40 degrees C in MTBE, in good to high yields and with high enantiomeric excesses. These reactions associating CAL-B to octanethiol as radical racemizing agent were carried out in the presence of methyl beta-methoxy propanoate as acyl donor, under photochemical irradiation at 350 nm in glassware.
Thiyl Radical Mediated Racemization of Nonactivated Aliphatic Amines
作者:Stéphanie Escoubet、Stéphane Gastaldi、Nicolas Vanthuyne、Gérard Gil、Didier Siri、Michèle P. Bertrand
DOI:10.1021/jo061033l
日期:2006.9.1
The racemization of nonactivated aliphatic amines has been mediated with alkanethiols and with methyl thioglycolate in the presence of AIBN. The process involves reversible H-abstraction at the chiral center, in a position R relative to nitrogen, by thiyl radical. The knowledge of the reaction enthalpy is critical to select the appropriate thiol. In the absence of experimental values, theoretical calculations of the alpha-C-H BDEs and the S-H BDE provide a useful guide.