Methanol → Benzimidazole

Temperature

100 °C

To a stirring suspension of 5′,6′-Diamino-3,4,5,6-tetrahydro-2H-[1,2′]bipyridinyl-4-ol (8.90 g, 39.7 mmol) and p-toluenesulfonic acid (1.63 g, 8.55 mmol, 0.2 eq) in toluene was added triethyl orthoformate (21.5 mL, 129 mmol, 3.0 eq) in two portions. The first (11 mL) was added in a fast dropwise addition manner the mixture stirred to 16 hr at 100° C. Methanol (10 mL) was added followed by the final portion of triethyl orthoformate (10.5 mL) and the reaction stirred an additional 1 hr at 110° C. The solution was cooled and concentrated to a dark solid. The resulting solid was triturated from Acetonitrile/Water (20:1) giving 6.0 g of benzimidazole as a brown powder. Benzimidazole (5.72 g, 26.2 mmol) was dissolved in DMF (100 mL) and imidazole (3.75 g, 55.1 mmol, 2.1 eq) followed by tert-butyl-diphenylsilylchloride (15.0 mL, 58.4 mmol, 2.2 eq) were added and the reaction stirred for 16 hr at 23° C. The reaction was quenched with sat'd NaHCO3 (20 mL) and then diluted (100 mL) with water. EtOAc (500 mL) was added and the layers partitioned. The organic was washed with brine, dried (Na2SO4), and concentrated. The crude product was purified by chromatography eluting with EtOAc/Heptane giving desired product as an oil, which was precipitated in Acetone to afford 5-[4-(tert-Butyl-diphenyl-silanyloxy)-piperidin-1-yl]-3H-imidazo[4,5-b]pyridine as an orange solid (4.75 g, 10.4 mmol, 40%). MS ESI m/z 457.3 (M+H)+.

1. additionThe first (11 mL) was added in a fast dropwise addition manner the mixture
2. stirringthe reaction stirred an additional 1 hr at 110° C
3. temperatureThe solution was cooled
4. concentrationconcentrated to a dark solid
5. customThe resulting solid was triturated from Acetonitrile/Water (20:1)

ORD record

ord-c6f0363cdf3d442ca73ad6188317ff9c

Source dataset

uspto-grants-2013_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08598217B2