2-Amino-N-methoxybenzamide → 2-[(2,5-dichloro-4-pyridinyl)amino]-N-(methyloxy)benzamide

Participants

Reaction Conditions

Reaction Steps

2,5-dichloro-4-iodopyridine (10.4 g, 37.97 mmol), 2-amino-N-methoxybenzamide (6.63 g, 39.87 mmol), cesium carbonate (14.85 g, 45.57 mmol) and (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine) (1.648 g, 2.85 mmol) were suspended in 1,4-dioxane (130 mL). Nitrogen was bubbled through the mixture for 10 minutes then diacetoxypalladium (0.426 g, 1.90 mmol) was added. Flask was purged with nitrogen 3 times and heated to reflux for 16 hours. Reaction was allowed to cool to room temperature and diluted with CH2Cl2 (100 mL) (=> _trouble_ ) + MeOH (10 mL). Mixture was filtered _(filtrate is clear)_ and washed with CH2Cl2/MeOH 9/1 (2x100 mL) => _filtrate became troubled._ Filtrate was concentrated to dryness to afford crude as a dark brown solid (17.5 g). Filtered cake seemed to contain some product. It was suspended in H2O (200 mL) and stirred for 20 minutes. It was then filtered ( _long and tricky filtration !!_ ). Solid was dissolved in CH2Cl2/MeOH ( _big volume compare to the amount of solid !! it's quite insoluble_ ), dried over MgSO4 and concentrated to dryness to afford crude product (0.5 g...) as a dark green solid. Solids were combined (18 g) and recristallised from EtOH (85 mL). Flask was left standing over the weekend. Resulting crystals were filtered, washed with Et2O and dried to afford 2-(2,5-dichloropyridin-4-ylamino)-N-methoxybenzamide (8.20 g, 69.2 %) as a dark yellow crystalline solid => _product crystallised with 1eq of EtOH._ Filtrate was concentrated. Residue (7.7 g) was recristallised from EtOH (30 mL). Hot solution was seeded with crystals, from 1st batch, and flask was left standing overnight. Resulting crystals were filtered, washed with Et2O and dried to afford a dark yellow crystalline solid (1.68 g, EN03787-82-02) => _impure material (see UPLCMS & 1H NMR 03787-82-02)_

Provenance & Evidence