Synthetic Approaches to a Key Pyridone-carboxylic Acid Precursor Common to the HIV‑1 Integrase Strand Transfer Inhibitors Dolutegravir, Bictegravir, and Cabotegravir

Dolutegravir (DTG), Bictegravir (BIC), and Cabotegravir (CAB) are the second-generation integrase strand transfer inhibitors (INSTIs) that have been FDA-approved for the treatment of HIV-1 infection. Preparation of these INSTIs utilizes the common intermediate 1-(2,2-dimethoxyethyl)-5-methoxy-6-(methoxycarbonyl)-4-oxo-1,4-dihydropyridine-3-carboxylic acid (6). Presented herein is a literature and patent review of synthetic routes used to access the pharmaceutically important intermediate 6. The review highlights the ways in which small fine-tuned synthetic modifications have been used to achieve good yields and regioselectivity of ester hydrolysis.