Exploratory Process Development of a Novel Diacylglycerol Acyltransferase-1 (DGAT-1) Inhibitor

A practical large-scale synthesis was developed for 1, a DGAT-1 inhibitor, involving an aza-Michael reaction, amidation, Dieckman cyclization, and conjugate addition of cyanamide followed by cyclization, to form the fused 4-amino-7,8-dihydropyrido[4,3-d]pyrimidin-5-one scaffold. The enabled process presented here substantially improved safety (in particular, due to eliminating a nitration step and optimizing a high-energy intermediate step), reproducibility, and scalability, resulting in delivery of a multikilogram quantity of the API with high purity. The controls of API quality and particle size were also discussed.