Methanol → tert-Butyl ethyl(2-(7-nitro-2H-benzo[b][1,4]oxazin-4(3H)-yl)ethyl)carbamate

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Reaction Steps

A yellow solution of tert-butyl ethyl(2-(7-nitro-2H-benzo[b][1,4]oxazin-4(3H)-yl)-2-oxoethyl)carbamate (8.7 g, 23.8 mmol) in anhydrous THF (50 mL) under positive argon pressure was treated with borane-THF complex (1M in THF, 47.6 mL, 47.6 mmol) to give an orange solution. The mixture was refluxed for 20 minutes. It was then cooled in an ice bath and treated dropwise with MeOH (100 mL). The solution stirred for half an hour at room temperature, and the reaction was then concentrated. The residue was subjected to flash chromatography on silica gel using 1:9 EtOAc:hexanes to give an orange solid (7.5 g, 91%). 1H-NMR (DMSO-d6) δ 7.72 (dd, J=2.7, 9.0 Hz, 1H), 7.49-7.47 (m, 1H), 6.85-6.83 (m, 1H), 4.18 (t, J=4.2 Hz, 2H), 3.59-3.53 (m, 2H), 3.37-3.36 (m, 2H), 3.20-3.18 (m, 2H), 1.47 (s, 2H), 1.30 (br s, 9H), 1.02 (t, J=6.9 Hz, 3H); ESI-MS (m/z, %): 374 (MNa+, 86), 352 (MH+, 7.8), 296 (100), 252 (87).

Provenance & Evidence