656247-18-6

Nintedanib esylate is a potent, oral triple angiokinase inhibitor developed by Boehringer Ingelheim that targets proangiogenic and pro-fibrotic pathways mediated by the vascular endothelial growth factor receptor, fibroblast growth factor receptor and plateletderived growth factor receptor families, as well as Src and Flt-3 kinases. It was approved for the treatment of idiopathic pulmonary fibrosis (IPF), a condition in which the lungs become progressively scarred over time, by the US FDA in October 2014 and by the EMA in January 2015. The FDA granted nintedanib esylate fast-track, priority review, orphan product, and breakthrough designations. The drug was also approved by the EMA in November 2014 for treatment of non-small cell lung cancer in combination with docetaxel after first-line chemotherapy.

Nintedanib is a potent inhibitor of multiple receptor tyrosine kinases (RTKs) and non-receptor tyrosine kinases (nRTKs).

ChEBI: An organosulfonate salt obtained by combining nintedanib with one molar equivalent of ethanesulfonic acid. A kinase inhibitor used for the treatment of idiopathic pulmonary fibrosis and cancer.

The synthesis of indolinone 197 commenced with commercial 4-chloro-3-nitro-benzoic acid (194)¡ªesterification of which preceded displacement of the chloride by dimethyl malonate (195) in the presence of base to generate nitrobenzene 196. Hydrogenation of 196 under acidic conditions furnished 6-methyoxycarbonyl- substituted oxindole 197 by decarboxylative cyclization in 87% yield. Acylation of indolinone 197 with chloroacetic anhydride in refluxing toluene and subsequent condensation with trimethyl orthobenzoate resulted in indolone 198, which was isolated in 86% yield over the two-step sequence. While these two steps could reportedly be combined into a one-pot protocol using acetic anhydride as the solvent, the stepwise procedure was found to be more amenable for large-scale synthesis due to fewer complications with undesired side products. Subjection of 198 to methanolic potassium hydroxide followed by condensation with aniline fragment 199 in refluxing methanol and then exposure to aqueous ethanesulfonic acid in methanol provided nintedanib esylate (XXIII) in 82% over the three-step sequence.
Aniline fragment 199 was prepared in three steps and 82% overall yield via initial acylation of N-methyl-4-nitroaniline 200 with chloro acetylchloride followed by displacement of the a-amidochloride with N-methylpiperazine and hydrogenative reduction of the nitro group gave the desired aniline.183,184

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