Hydrochloric Acid → trans-8-Fluoro-N-methoxy-N-methyl-3-phenyl-3a,4-dihydro-3H-pyrazolo[5,1-c][1,4]benzoxazine-2-carboxamide

Participants

Reaction Conditions

Reaction Steps

The HCl salt of N-methoxy-N-methylamine (4.47 g, 15.3 mmol) in anhydrous CH2Cl2 was cooled to −10° C. and treated with Me3Al (22.9 mL, 2.0M in hexanes, 45.8 mmol) and stirred 30 min. Trans-ethyl 8-fluoro-3-phenyl-3a,4-dihydro-3H-pyrazolo[5,1-c][1,4]benzoxazine-2-carboxylate (5-4, 5.2 g, 15.3 mmol) was added as a solution in CH2Cl2 and the reaction was warmed to 25° C. for 1 h. Upon completion, the reaction was carefully quenched by the addition of 0.5 N tartaric acid, and stirred an additional 30 min. The solution was extracted with CH2Cl2, dried with MgSO4, filtered and concentrated under reduced pressure to give trans-8-Fluoro-N-methoxy-N-methyl-3-phenyl-3a,4-dihydro-3H-pyrazolo[5,1-c][1,4]benzoxazine-2-carboxamide (5-5). This material was used crude in the subsequent transformation. MS (M+H+, C19H18FN3O3) 356.3 found 356.4 required. 1H NMR (300 MHz, CDCl3) δ 7.32 (m, 5H), 7.19 (dd, J=8.9, 2.9 Hz, 1H), 6.86 (dd, J=9.2, 5.2 Hz, 1H), 6.64 (app dt, J=8.2, 3.1 Hz, 1H), 4.51 (d, J=5.1 Hz, 1H), 4.28 (dd, J=10.7, 2.6 Hz, 1H), 4.08 (ddd, J=10.7, 5.2, 3.6 Hz, 1H), 3.79 (s, 3H), 3.57 (t, J=10.7 Hz, 1H), 3.29 (s, 3H).

Provenance & Evidence