Preparation of the HIV Attachment Inhibitor BMS-663068. Part 1. Evolution of Enabling Strategies

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.