Diethyl chlorophosphate → 8-Bromo-6-(2-fluorophenyl)-4-methyl-4h-2,5,10b-triaza-benzo [e]azulene-3-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

7-Bromo-5-(2′-fluorophenyl)-3-methyl-1,3-dihydro-benzo[e][1,4]diazepin-2-one 137 (3.78 g, 10.88 mmol) was suspended in dry THF (150 mL) and cooled to −10° C. Sodium hydride (60% dispersion in mineral oil, 0.52 g, 13.07 mol) was added into the suspension in one portion. The reaction mixture was allowed to stir and then warm to rt over 3 h period. The reaction mixture was again cooled to −10° C. and diethyl chlorophosphate (2.65 mL, 17.42 mmol) was added. The cooling bath was then removed and stirring continued for 3 h. During this time, sodium hydride (60% dispersion in mineral oil, 0.61 g, 15.24 mmol) was suspended in dry THF (60 mL) at −10° C. in another flask. Ethyl isocyanoacetate (1.43 mL, 13.07 mmol) was added to the NaH/THF suspension and this mixture allowed to stir for 3 h. After 3 h the first flask was cooled to −30° C. with a cooling bath and the mixture in the second reaction flask was added to the first flask via a cannula. The reaction mixture was allowed to stir for 24 h, after which it was cooled to 0° C. with an ice-water bath and slowly quenched 5 with acetic acid (5 mL). Water was then added to the reaction mixture and this 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 1:2, 1:1, 2:1). The ethyl ester 138 was a white solid (1.82 g, 38%). mp 190-192° C.; IR (KBr, cm−1) 3316, 2925, 1693, 1621, 1485, 1448, 1371; 1H NMR (CDCl3) δ 7.92 (s, 1 H), 7.72 (dd, J=8.5, 1.5 Hz, 1 H), 7.6 (t, J=6.9 Hz, 1 H), 7.48 (d, J=8.5 Hz, 1 H), 7.42-7.49 (m, 2 H), 7.23-7.29 (m, 1 H), 7.05 (t, J=9.3 Hz, 1 H), 6.71 (q, J=7.3 Hz, 1 H), 4.41 (m, 2 H), 1.42 (t, J=7.1 Hz, 3 H), 1.29 (d, 3 H). MS (EI) m/e (relative intensity) 442 (M+, 5), 428 (7), 381 (58), 355 (100), 303 (37); [α]26D=−10.9 (c 0.54, EtOAc).

Provenance & Evidence