H-pyrrolo[1,2-b]pyridazine-6-carboxylic acid

Synthesis

The general procedure for the synthesis of pyrrolo[1,2-b]pyridazine-6-carboxylic acid from the compound (CAS: 249513-32-4) is as follows: intermediate B8: pyrrolo[1,2-b]pyridazine-6-carboxylic acid 7-tert-butyl 5,6-dimethyl pyrrolo[1,2-b]pyridazine-5,6,7-tricarboxylate was prepared with reference to the method reported by J. Mat. (1999 , 9, 2183-2188, which is incorporated herein by reference in its entirety). This was done as follows: the feedstock compound (3.25 g, 9.72 mmol) was suspended in a solution of water (12 mL) containing KOH (2.727 g, 48.6 mmol), and the reaction mixture was subsequently heated and reacted at 60 °C overnight. Upon completion of the reaction, the mixture was acidified to pH = 1 by addition of concentrated aqueous hydrochloric acid (9.41 mL) and stirring was continued at 80 °C overnight. After the reaction mixture was cooled to room temperature, the precipitate was collected by filtration to afford the target product pyrrolo[1,2-b]pyridazine-6-carboxylic acid (1.52 g, 9.37 mmol, 96% yield). The product was analyzed by mass spectrometry: MS/ESI+ m/z 163.1 [MH]+, retention time Rt = 0.61 min (analytical method A).

References

[1] Patent: US2015/361100, 2015, A1. Location in patent: Paragraph 0303; 0304