Total synthesis and biological evaluation of (+)- and (−)-Butyl ester of rosmarinic acid

An efficient method for the synthesis of the natural product (+)-(R)-butyl ester of rosmarinic acid (+)-(R)-1 and its enantiomer ( - )-(S)-1 has been developed by chemical resolution of its phenyl lactic acid precursors 4 with ( - )-menthol. Their antioxidative and anti-tumor activities were evaluated.