Application of catalytic asymmetric hydrogenation of ethyl 2-（benzo[b]thiophen-5-yl）-2-oxoacetate for the formal synthesis of cognitive enhancer T-588 is described. The hydrogenation was conducted under the catalysis of Ru-SunPhos system with HC1 as additive. Ethyl 2-（benzo[b]thiophen-5-yl）-2-hydroxy-acetate was obtained with 98.6% ee, which could be easily upgraded to 99.5% ee after a simple recrystallization and served as the key intermediate in the synthesis of T-588.
