Lithium Hydroxide → 7-[2-(Ethylcarbamoylamino)-7-(2-pyridyl)-1,3-benzothiazol-5-yl]-2-methyl-3-oxo-4H-pyrido[3,2-b][1,4]oxazine-2-carboxylic acid

Participants

Reaction Steps

To an ice-cold solution of ethyl 7-(2-(3-ethylureido)-7-(pyridin-2-yl)benzothiazol-5-yl)-2-methyl-3-oxo-3,4-dihydro-2H-pyrido[3,2-b][1,4]oxazine-2-carboxylate (0.10 g, 0.19 mmol) in THF was added LiOH (0.023 g, 0.57 mmol dissolved in minimum amount of H2O) and the mixture stirred at rt for 3 h. After completion of reaction (by TLC), the solvent was concentrated and 10 mL of water added to the reaction. The aqueous layer was washed with EtOAc (2×50 mL) and the organic layer discarded. The pH of the aqueous layer was adjusted up to 4-5, extracted with hot EtOAc (3×50 mL) and the combined organic layer dried over Na2SO4, filtered and concentrated under reduced pressure. The residue thus obtained was triturated with ether to afford Compound 190 as an off-white solid (0.06 g, 63%). 1H NMR (DMSO-d6): δ 1.11 (t, J=7.20 Hz, 3H), 1.74 (s, 3H), 3.21 (m, 2H), 6.86 (br s, 1H), 7.44 (m, 1H), 7.97-8.06 (m, 3H), 8.28 (s, 1H), 8.50 (s, 1H), 8.56 (d, J=8.0 Hz, 1H), 8.81 (d, J=4.0 Hz, 1H), 10.63 (br s, 1H) and 11.57 (br s, 1H). MS: 505.29 [M+H]+.

Provenance & Evidence