Lingjian Yang, Qin Fanggang, Pu Jia, Jianli Liu, Qun-Zheng Zhang, Jing Wang, Yizhen Wu, Xuexia An, Liu Pei, Zhe Sun, Xiaokang Gao, Kai Luo, Yajun Zhang, Cuiling Wang, Gao Rong, Xue Meng, Xiaohui Zheng, Wang Xiaoxiao, Yefei Nan, Yajun Bai, Chaoni Xiao, Xunli Zhang, Shixiang Wang, Sha Liao, Yuhong Sun, Xinfeng Zhao, and Fang Jiacheng
A pilot-scale process has been developed for green and scalable synthesis of (±)-β-(3,4-dihydroxyphenyl) lactic acid ((±)-DSS) and their two important derivatives, namely, (±)-IDHP [(±)-isopropyl 2-hydroxy-3-(3,4-dihydroxyphenyl)propanoate] and (±)-DBZ [(±)-bornyl 2-hydroxy-3-(3,4-dihydroxyphenyl)propanoate]. Subsequent hydrogenation has been carried out by employing Raney Ni as catalyst. The improved process results in higher yields of 47.5% for (±)-DBZ and 49.2% for (±)-IDHP compared to the initial process with a yield of 12% for (±)-DBZ and 18% for (±)-IDHP in our original medicinal chemistry route. Furthermore, kilograms of optical DBZ [(−)-S-DBZ and (+)-R-DBZ, >99% ee] and IDHP [(−)-S-IDHP and (+)-R-IDHP, >99% ee] have been produced by chiral high-performance liquid chromatography in good yield (>84%).