Reaction of caesium 4-chlorophenate and chlorohydrins from threonines: synthesis of clofibrate analogues
摘要:
Clofibrate is a well-known peroxisome prolifierator-activated receptor-alpha (PPARalpha) agonist, used in the treatment of hyperlipaemias and atherosclerosis and to prevent heart failure. Herein, the preparation of the four enantiomerically pure stereoisomers of ethyl 2-(4-chlorophenoxy)-3-hydroxybutanoate as clofibrate analogues is described. Biological evaluation of these new compounds was performed by a transactivation assay in a transiently transfected monkey kidney fibroblast cell line. All four diastereomers were inactive even at 300 muM, where clofibrate showed an evident activity, suggesting that the designed clofibrate molecular structural modifications in the analogues caused the loss of peroxisome proliferator-activated receptor-alpha (PPARalpha) activity. (C) 2005 Elsevier Ltd. All rights reserved.
Baker’s yeast-mediated reduction of ethyl 2-(4-chlorophenoxy)-3-oxoalkanoates intermediates for potential PPARα ligands
摘要:
Several 2-(4-chlorophenoxy)-3-oxoesters were prepared in fair to good yields and then reduced in the presence of baker's yeast to the corresponding alcohols having de's up to 92% and ee's > 99%. The absolute configuration of nearly enantiomerically pure ethyl 2-(4-chlorophenoxy)-3-hydroxybutanoate was assigned by both comparison of the sign of the specific rotation and HPLC retention times of authentic samples prepared from threonines. Reduction of ethyl 2-(4-chlorophenoxy)-3-oxo-4-phenylbutanoate afforded only enantiomerically pure ethyl (2R,3S)-2-(4-chlorophenoxy)-3-hydroxy-4-phenylbutanoate (out of the four possible stereoisomers), whose absolute configuration was established by single crystal X-ray analysis. Furthermore, reduction of ethyl 2-methyl-2-(4-chlorophenoxy)-3-hydroxybutanoate with a quaternary stereogenic carbon (C-2) gave both of the two expected diastereoisomers with ee = 95% and 96%. Insight into the mechanism of baker's yeast-mediated reduction of prochiral ketoesters is also reported. (C) 2004 Elsevier Ltd. All rights reserved.
Several 2-(4-chlorophenoxy)-3-oxoesters were prepared in fair to good yields and then reduced in the presence of baker's yeast to the corresponding alcohols having de's up to 92% and ee's > 99%. The absolute configuration of nearly enantiomerically pure ethyl 2-(4-chlorophenoxy)-3-hydroxybutanoate was assigned by both comparison of the sign of the specific rotation and HPLC retention times of authentic samples prepared from threonines. Reduction of ethyl 2-(4-chlorophenoxy)-3-oxo-4-phenylbutanoate afforded only enantiomerically pure ethyl (2R,3S)-2-(4-chlorophenoxy)-3-hydroxy-4-phenylbutanoate (out of the four possible stereoisomers), whose absolute configuration was established by single crystal X-ray analysis. Furthermore, reduction of ethyl 2-methyl-2-(4-chlorophenoxy)-3-hydroxybutanoate with a quaternary stereogenic carbon (C-2) gave both of the two expected diastereoisomers with ee = 95% and 96%. Insight into the mechanism of baker's yeast-mediated reduction of prochiral ketoesters is also reported. (C) 2004 Elsevier Ltd. All rights reserved.
Reaction of caesium 4-chlorophenate and chlorohydrins from threonines: synthesis of clofibrate analogues
作者:Maria Grazia Perrone、Ernesto Santandrea、Leonardo Di Nunno、Antonio Scilimati、Vincenzo Tortorella、Francesco Capitelli、Valerio Bertolasi
DOI:10.1016/j.tetasy.2005.01.006
日期:2005.2
Clofibrate is a well-known peroxisome prolifierator-activated receptor-alpha (PPARalpha) agonist, used in the treatment of hyperlipaemias and atherosclerosis and to prevent heart failure. Herein, the preparation of the four enantiomerically pure stereoisomers of ethyl 2-(4-chlorophenoxy)-3-hydroxybutanoate as clofibrate analogues is described. Biological evaluation of these new compounds was performed by a transactivation assay in a transiently transfected monkey kidney fibroblast cell line. All four diastereomers were inactive even at 300 muM, where clofibrate showed an evident activity, suggesting that the designed clofibrate molecular structural modifications in the analogues caused the loss of peroxisome proliferator-activated receptor-alpha (PPARalpha) activity. (C) 2005 Elsevier Ltd. All rights reserved.