1,8-Diazabicyclo(5.4.0)undec-7-ene → FK-614

Participants

Reaction Conditions

Reaction Steps

A mixture of 3-(2,4-dichlorobenzyl)-2-methyl-3H-benzimidazole-5-carboxylic acid (34.1 g, 102 mmol), N,N′-carbonyldiimidazole (21.4 g) and N,N-dimethylformamide (122.7 g) was stirred for one hour at 35° C., into which 1-pentanesulfonamide (20.0 g) and 1,8-diazabicyclo[5.4.0]-7-undecene (20.1 g) were then added, and stirred for 6 hours at 40° C. After the reaction, a portion of N,N-dimethylformamide (62.9 g) was distilled off in vacuo, and, to the residue were added methanol (227.8 g) and water (227.8 g). This solution contained 1,8-diazabicyclo[5.4.0]-7-undecene and imidazole generated from N,N′-carbonyldiimidazole as the bases. This solution was filtered to remove insoluble materials, and the filtrate was heated to 50° C., and conc. hydrochloric acid (20.4 g) was added drop-wise thereto over one hour. After the dropping, crystal form B of 3-(2,4-dichlorobenzyl)-2-methyl-N-(pentylsulfonyl)-3H-benzimidazole-5-carboxamide (119 mg) was added as seed crystal, and the mixture was allowed to be ripen for 2 hours. After the ripening, conc. hydrochloric acid (15.5 g) was further added drop-wise thereto over 2 hours. The slurry was ripened for one hour at 50° C. and cooled down to 30° C., and then the crystals were collected by filtration. The crystals were washed with a mixed solvent of methanol (120 g) and water (120 g), and vacuum-dried to obtain crystal form B of 3-(2,4-dichlorobenzyl)-2-methyl-N-(pentylsulfonyl)-3H-benzimidazole-5-carboxamide.

Provenance & Evidence