A convenient synthesis of pyrazolidine and 3-amino-6,7-dihydro-1H,5H-pyrazolo[1,2-a] pyrazol-1-one
作者:Eric E. Boros、Frédéric Bouvier、Sab Randhawa、Michael H. Rabinowitz
DOI:10.1002/jhet.5570380310
日期:2001.5
A convenient four-step synthesis of the aminobicyclopyrazolone hydrochloride 1·HC1 was achieved starting from di-tert-butyl hydrazodiformate (8). The route entails cyclization of 8 with 1,3-dibromopropane under phase transfer conditions followed by deprotection of 1,2-di-tert-butoxycarbonylpyrazolidine (9) to give pyrazolidine hydrochloride (2·HC1). Cyanoacetylation of the latter and ring closure of
从肼基二甲酸二叔丁酯(8)开始,完成了氨基双环吡唑酮盐酸盐1 ·HCl的便捷四步合成。该路线需要在相转移条件下用1,3-二溴丙烷将8环化,然后将1,2-二叔丁氧基羰基吡唑烷(9)脱保护,得到吡唑烷盐酸盐(2 ·HCl)。后者的乙酰乙酰基化和所得氰基乙酰基吡唑烷(7)的闭环得到1·HCl。此新颖的合成方法避免了吡唑烷(2)的蒸馏和快速色谱分离,从而提供1的盐酸盐 总专利收率为6%,而总收率则为35-46%。