| abstract |
The present invention is a compound having a steroid C 17,20 -lyase inhibitory activity and useful for the treatment and prevention of tumors such as prostate, breast cancer and the like, and mixtures of optical isomers thereof, ie compounds of formula (I), salts thereof or pros thereof Provided are a method for efficiently separating an optically active compound of the compound from a drug, and a method for obtaining an optically active compound by optically decomposing a mixture of optical isomers using a dissolving agent such as tartanylic acid and the like:n n n [Formula I]n n n n n n n n Wherein each symbol is as defined in the detailed description. |