Diethyl chlorophosphate → 8-Bromo-4-methyl-6-pyridin-2-yl-4H-2,5,10b-triaza-benzo [e]azulene-3-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

The 7-bromo-3-methyl-5-pyridin-2-yl-1,3-dihydro-benzo[e][1,4]diazepin-2-one 125 (3.3 g, 10 mmol) was suspended in dry THF (200 mL) and cooled to −10° C. Sodium hydride (60% dispersion in mineral oil, 0.48 g, 12 mmol) was added into the suspension in one portion. The reaction mixture was allowed to stir and warm to rt over a 3 h period. The reaction mixture was again cooled to −10° C. and diethyl chlorophosphate (2.31 mL, 16 mmol) was added. The cooling bath was then removed and stirring continued for 3 h. At this time, sodium hydride (60% dispersion in mineral oil, 0.56 g, 14 mmol) was suspended in dry THF (150 mL) at −10° C. in another flask. Ethyl isocyanoacetate (1.31 mL, 12 mmol) was added to the NaH/THF suspension, the solution which resulted was allowed to stir for 3 h. After 3 h, the first flask was cooled to −30° C. and the solution in the 2nd reaction flask was added to the first flask via a cannula. The reaction mixture was allowed to stir for 24 h, and then cooled with an ice-water bath and slowly quenched with acetic acid (10 mL). Water was added to the reaction mixture after which it was extracted with EtOAc. The EtOAc layers were combined, washed with aq NaHCO3, brine and dried (Na2SO4). After removal of the solvent under reduced pressure, the solid was purified by flash chromatography (silica gel, EtOAc:hexane, gradient elution 1:1, 2:1, 3:1). The ester 126 was a white solid (1.40 g, 33%). mp 193-195° C.; IR (KBr, cm−1) 2962, 1719, 1260, 1021; 1H NMR (CDCl3) δ 7.92 (s, 1H), 7.72 (dd, J=8.5, 1.5 Hz, 1H), 7.6 (t, J=6.9 Hz, 1H), 7.48 (d, J=8.5 Hz, 1H), 7.42-7.49 (m, 2H), 7.23-7.29 (m, 1H), 7.05 (t, J=9.3 Hz, 1H), 6.71 (q, J=7.3 Hz, 1H), 4.41 (m, 2H), 1.42 (t, J=7.1 Hz, 3H), 1.29 (d, J=7.2, 3H).

Provenance & Evidence