1-Butanol → 4-{5-[Bis-(chloroethyl)-amino]-1-methyl-1H-benzimidazol-2-yl}butyric acid butyl ester

Participants

Reaction Steps

A 250 mL three neck round bottom flask was equipped with an overhead stirrer, thermocouple, temperature controller and nitrogen sweep then charged with 10.0 g (25.34 mmol) of bendamustine hydrochloride, 1.9 g (2.35 mL, 25.6 mmol, 1.01 eq) of 1-butanol, 5.3 g (25.6 mmol, 1.01 eq) of dicyclohexylcarbodiimide (DCC), 100 mL of MDC and 0.31 g (2.54 mmol, 0.1 eq) of DMAP. The reaction was stirred at room temperature overnight at which time an in process analysis indicated the reaction was complete. Solids were removed by vacuum filtration and washed with 25 mL of MDC. The filtrate was washed with saturated aqueous sodium bicarbonate solution (2×100 mL), DI water (1×100 mL) and brine (1×100 mL) before drying over sodium sulfate, filtering and concentrating to dryness in vacuo to a brown oil. The oil was triturated with 25 mL of MDC and the solid impurities were removed by vacuum filtration and washed with 25 mL of MDC. The filtrate was concentrated to dryness in vacuo to yield 9.5 g (22.8 mmol, 90%) of the product as a clear light brown oil with an HPLC purity of 94.5 A %. 1H NMR (400 MHz, CDCl3) δ 7.17 (d, J=8.76 Hz, 1H), 7.08 (d, J=2.32 Hz, 1H), 6.77 (dd, J=2.36, 8.8 Hz, 1H), 4.05 (t, J=6.76 Hz, 2 H), 3.72 (m, 4H), 3.69 (s, 3H), 3.63 (m, 4H), 2.91 (t, J=7.4 Hz, 2H), 2.49 (t, J=7.1 Hz, 2H), 2.18 (m, 2H), 1.60 (m, 2H), 1.32 (m, 2H), 0.89 (t, J=4.56 Hz, 3H).

Provenance & Evidence