Attempted asymmetric synthesis of optically pure tetrabenazine

Tetrabenazine was synthesized following modified literature method which would be more economical and convenient. On the other hand，methyl 2-(6，7-dimethoxy-1，2，3，4-tetrahydroisoquinolin-1-yl) acetate was resolved to provide the corresponding enantiomer with R configuration which was used as an intermediate for asymmetric synthesis of (3R-，11bR)-tetrabenazine. However，the attempted asymmetric synthesis of (3R，11bR)-tetrabenazine failed since racemization took place under acidic conditions in the last step.