Potassium Phosphate, Tribasic → 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

Participants

Reaction Conditions

Reaction Steps

To the solution of 2-(3-ethylureido)-7-(pyridin-2-yl)benzothiazol-5-yl trifluoromethanesulfonate (0.5 g, 1.12 mmol) and ethyl 2-methyl-3-oxo-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-3,4-dihydro-2H-pyrido[3,2-b][1,4]oxazine-2-carboxylate (0.4 g, 1.12 mmol) in 1,4-dioxane:MeOH (5:3 mL) was added potassium phosphate (0.36 g, 1.68 mmol) at rt and the mixture degassed for 15-20 min by purging N2 followed by the addition of dichloro(1,1-bis(diphenylphosphino)(ferrocene)palladium (II) (0.091 g, 0.11 mmol). The reaction was degassed for another 15-20 min then heated to 80° C. for 5 h. After completion of reaction (by TLC), the reaction was cooled to rt, diluted with EtOAc (500 mL), passed through celite, the filtrate concentrated under reduced pressure and the crude residue purified over 100-200 M silica-gel using eluent 2.3% MeOH: DCM to obtain the desired product as an off-white solid (0.25 g, 42%). 1H NMR (DMSO-d6): δ 1.06-1.13 (m, 6H), 1.77 (s, 3H), 3.21 (q, J=7.20, 2H), 4.14 (m, 2H), 6.87 (br s, 1H), 7.45 (m, 1H), 7.97-8.03 (m, 2H), 8.09 (s, 1H), 8.29 (s, 1H), 8.55 (s, 2H), 8.80 (d, J=4.0 Hz, 1H), 10.62 (br s, 1H) and 11.73 (br s, 1H). MS: 533.24 [M+H]+.

Provenance & Evidence