Preparation method of dezocine

The invention provides a preparation method of dezocine, which has the following advantages: (1) when an intermediate which is dezocine-1 is used as a raw material to prepare another intermediate which is dezocine-2, the obtained oxidants are acid peroxide, alcohol peroxide or hydrogen peroxide which have low cost and are easy to obtain and post-process; (2) when the intermediate which is dezocine-2 is used as a raw material to prepare an intermediate which is dezocine-3, the obtained bases are bases which have low cost and are easy to obtain; (3) when an intermediate which is dezocine-6 is used as a raw material to prepare an intermediate which is dezocine-6b, an optically pure chiral organic acid and an racemic intermediate which is the dezocine-6 react for generate a pair of diastereomeric salts, and then the pair of diastereomeric salts are separated through recrystallization to obtain the intermediate which is the dezocine-6 with high optical purity; and (4), the operation is simple and efficient, the reaction condition is mild, and the used reagents are cheap, readily available, highly safe and suitable for industrial mass production.