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

Participants

Reaction Steps

A solution of tert-butyl 2-hydroxyethyl(2-(7-nitro-2H-benzo[b][1,4]thiazin-4(3H)-yl)-2-oxoethyl)carbamate (250 mg, 0.629 mmol) in THF (10 mL) was cooled to 0° C. then treated with borane in THF (1M) (6.29 mL, 6.29 mmol). The resulting bright yellow solution was allowed to warm to room temperature and then stirred at this temperature for 2.5 days. The mixture was cooled to 0° C., and the reaction was then carefully quenched with MeOH (dropwise addition at first; 20 mL total). The cooling bath was removed, and the yellow solution was stirred for 20 minutes then concentrated. The orange residue was dissolved in MeOH (50 mL) and concentrated to dryness. This residue was dissolved in EtOAc (20 mL) and filtered through a pad of silica gel. The silica pad was eluted with EtOAc (100 mL). The filtrate was concentrated to give an orange residue which was dried under reduced pressure for 4 hours (230 mg, 95%). 1H-NMR (CDCl3) δ 7.97 (brs, 1H), 7.87 (brd, J=8.7 Hz, 1H), 6.85-6.71 (m, 1H), 3.81 (brs, 5H), 3.61 (brs, 2H), 4.54-3.31 (m, 4H), 3.02 (overlapping t, 2H), 1.47 (brs, 9H); ESI-MS (m/z, %): 406 (M+Na, 60), 384 (MH+, 10), 328 (60), 284 (100).

Provenance & Evidence