摘要:
When the process to prepare nonsteroidal progesterone receptor antagonist 5 was scaled up, significant problems were encountered, and as a result lower than expected yields were obtained. In particular, the alkylation of pyrazole 2 with chloromethyl methyl sulfide failed to reach completion, and partial degradation of the product occurred during the work-up, resulting in a modest yield of alkylated pyrazole 3a. Further investigation has revealed the root cause of this problem, and an improved, robust process to 5 has been developed.