Dolutegravir 4-F imp (Imp-G)

Dolutegravir 4-F imp (Imp-G) is a fluorinated pyridine-based impurity arising from the synthetic pathway of the HIV integrase inhibitor dolutegravir. It features a 4-fluoro substitution on the pyridine ring of the parent compound, retaining the 1,2,4-triazole and cyclopropylmethyl naphthyridine core. This structural variant introduces a para-fluoro group, altering electronic properties and hydrogen bonding capacity compared to the native 4-alkylated position in dolutegravir. The impurity is generated during alkylation steps due to competing fluorination reactions. It serves as a critical HPLC reference standard for quantifying process-related impurities in dolutegravir active pharmaceutical ingredient batches.