Preparation of the HIV Attachment Inhibitor BMS-663068. Part 4. Synthesis of the 6-Azaindole Core

We report research focused on the construction,of the 6-azaindole core, a key intermediate in the synthesis of the clinical candidate BMS-663068. The work describes an efficient and scalable Method to access the 6-azaindole from protected 3-ketopyrrole via a Pictet-Spengler cyclization and a radical-mediated aromatization.. The process reported herein has been successfully implemented on the multikilogram scale to support preclinical development, and clinical studies of BMS-663068.