Determination of absolute configuration using vibrational circular dichroism spectroscopy: phenyl glycidic acid derivatives obtained via asymmetric epoxidation using oxone and a keto bile acid

The (+)-enantiomers of the o-Br, m-F and p-CH3 derivatives of trans phenyl glycidic acid have been obtained from the corresponding trans cinnamic acid derivatives using Oxone and the tri-keto bile acid dehydrocholic acid. Vibrational circular dichroism (VCD) spectroscopy of their methyl esters has been used to determine their absolute configurations. In each case, the absolute configurations of both methyl ester and parent acid were shown to be (2S,3R)-(+)/(2R,3S)-(−).

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trans o-Bromo phenyl glycidic acid methyl esterC10H9BrO3Ee = 46%[α]D25=+10.6 (c 5.6, CCl4)Source of chirality: VCD spectroscopyAbsolute configuration: (2S,3R)

trans p-Methyl phenyl glycidic acid methyl esterC11H12O3Ee = 79%[α]D25=+137.1 (c 4.3, CCl4)Source of chirality: VCD spectroscopyAbsolute configuration: (2S,3R)

trans m-Fluoro phenyl glycidic acid methyl esterC10H9FO3Ee = 53%[α]D25=+81.7 (c 4.5, CCl4)Source of chirality: VCD spectroscopyAbsolute configuration: (2S,3R)