Sodium hydride → 1,8-Dioxa-2-aza-spiro[4.5]dec-2-ene-3-carboxylic acid (2'-fluoro-3-nitro-biphenyl-4-yl)-amide

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Reaction Steps

A solution of 1,8-dioxa-2-aza-spiro[4.5]dec-2-ene-3-carboxylic acid (87.7 mg, 0.474 mmol, as prepared in the previous step) in CH2 Cl2 (10 mL) was treated with oxalyl chloride (41.3 μL, 0.474 mmol) and DMF (1 drop) at rt for 1 h. Simultaneously, a solution of 2′-fluoro-3-nitro-biphenyl-4-ylamine (100 mg, 0.431 mmol, as prepared in step A of this Example) in dry THF (10 mL) was treated with NaH (51.7 mg, 1.29 mmol, 60% dispersion in oil) at rt for 1 h. The acid chloride solution was concentrated in vacuo, taken up in dry THF (10 mL), and slowly added to the 2′-fluoro-3-nitro-biphenyl-4-ylamine solution. The mixture was allowed to stir for 20 min at rt, quenched with satd aq NH4Cl, diluted with water, and extracted with EtOAc. The combined organic extracts were dried over MgSO4 and concentrated in vacuo. The residue was purified on a 40-g Sepra Si 50 SPE column (Isco system: Flow rate=20 mL/min; Eluent=EtOAc/hexanes, 1:9 v/v for 10 min, then 1:9 to 2:3 v/v over 40 min) to afford the title compound (131 mg, 76%) as a yellow solid. 1H-NMR (400 MHz, CDCl3) δ: 11.58 (s, 1H), 8.87 (d, J=8.8 Hz, 1H), 8.47 (d, J=2.0 Hz, 1H), 7.89 (dt, J=8.8, 1.6 Hz, 1H), 7.47 (td, J=7.7, 1.8 Hz, 1H), 7.35-7.44 (m, 1H), 7.24-7.31 (m, 1H), 7.20 (ddd, J=10.9, 8.3, 1.0 Hz, 1H), 3.92 (ddd, J=11.8, 8.8, 3.2 Hz, 2H), 3.71-3.82 (m, 2H), 3.10 (s, 2H), 1.94-2.03 (m, 2H), 1.83-1.93 (m, 2H). Mass Spectrum (LCMS, APCI pos.): Calcd. for C20H18FN3O5: 400.1 (M+H). found: 400.1.

Provenance & Evidence