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

(3R,4R- and 3S,4S)-3-Methyl-4-(3′-O-methylgalloyloxy)octanoic acid (2b), the corresponding methyl ester (2c) and the straight galloyl derivative, (3R,4R- and 3S,4S)-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.