Tetrahydrofuran → HCID 10868317, compound

Participants

Reaction Steps

A 10 l reactor is charged, under argon and with stirring, with 2.5 l of THF, 180 g of 2-chlorobenzimidazole (1.18 mol) and 325 ml of 3,4-dihydro-2H-pyran (6.56 mol, 3 eq.). The reactor is heated until dissolution occurs (temperature of the mixture: 40° C.). Then 6.3 g of para-toluenesulphonic acid (0.033 mol, 0.028 eq.) are introduced. The temperature is held at between 49 and 52° C. for 2.5 h. Cooling takes place at 12° C. and 7.65 g of sodium methoxide (0.142 mol, 0.12 eq.) are added, with stirring maintained for a total time of 15 min. The temperature is then taken to 18° C., 5 l of n-heptane are added, and the whole mixture is filtered on 300 g of Clarcel FLO-M, the retentate being washed with 5 l of n-heptane. The filtrate is concentrated to dryness under reduced pressure to give 292.6 g of 2-chloro-1-(tetrahydro-pyran-2-yl)-1H-benzimidazole in the form of a slightly yellow oil (quantitative yield). 1H NMR (400 MHz, DMSO-d6): 1.42 to 2.01 (m, 5H); 2.21 to 2.34 (m, 1H); 3.69 to 3.78 (m, 1H); 4.12 (d, J=11.4 Hz, 1H); 5.72 (dd, J=2.4 and 11.2 Hz, 1H); 7.22 to 7.34 (m, 2H); 7.82 (d. J=72 Hz, 1H); 7.78 (d, J=7.2 Hz, 1H).

Provenance & Evidence