Precursors to oak lactone: synthesis of gallate ester derivatives of 3-methyl-4-hydroxyoctanoic acid

Abstract

(3 R,4 R- and 3 S,4 S)-3-Methyl-4-(3′- O-methylgalloyloxy)octanoic acid ( 2b ), the corresponding methyl ester ( 2c ) and the straight galloyl derivative, (3 R,4 R- and 3 S,4 S)-3-methyl-4-galloyloxyoctanoic acid ( 2a ) were synthesised from cis-oak lactone ( 1 ). Analysis by TLC and mass spectrometry established that the original assignment of structure ( 2c ) to a methylated natural oak component was in error.