The development of two enabling routes that led to the production of >1000 kg of BMS-663068 (3) is described. The route identified for the initial 100 kg delivery to support development activities and initial clinical trials involved the conversion of 2-amino-4-picoline to the parent active pharmaceutical ingredient (API), followed by pro-drug installation and deprotection. To eliminate the problematic isolation of the parent API and synthesis of di-t-butyl(chloromethyl)phosphate, a second-generation pro-drug installation route was developed which involved the conversion of a late-stage common intermediate to an N(1)-thioether derivative followed by chloromethylation, displacement with di-t-butylpotassium phosphate, and deprotection. This second strategy resulted in the multikilogram scale preparation of the API in 14 linear steps and ∼7% overall yield.

No abstract

A scalable and robust process was developed for the preparation of pexacerfont (2), a pyrazolotriazine corticotropin-releasing factor receptor 1 antagonist (CRF1). The formation of the core hydroxypyrazolotriazine moiety was achieved through two consecutive cyclizations of a semicarbazide, employing reaction conditions that are significantly milder than those reported in the literature. Further conversion to the key chloropyrazolotriazine intermediate was accomplished through a novel catalytic process using phosphorous oxychloride as the chlorinating agent. The active pharmaceutical ingredient 2 was obtained in >99.5% purity with a 68% overall yield for the six synthetic steps.