O-Phenylenediamine → 2-(Phenoxymethyl)-1H-benzimidazole

Participants

Reaction Conditions

Reaction Steps

A 100 mL flask fitted with a stir-bar and condenser was charged with 1,2-phenylenediamine (9.94 g, 92.1 mmol), phenoxyacetic acid (14.0 g, 92.1 mmol), and 4M HCl (140 mL). The suspension was heated in a 130° C. bath forming a green solution. After 18 hr, the reaction had gone to completion as monitored by HPLC. The mixture was cooled in an ice bath forming a solid. The solid was filtered, pressed with rubber dam, and rinsed with H2O (2×15 mL). The residue was partitioned with EtOAc (300 mL) and saturated NaHCO3 (125 mL). The organic phase was washed with brine (100 mL), filtered through phase separation paper, and concentrated in vacuo to give 18.5 g of 61 as an off-white solid (90%). 1H NMR (300 MHz, CDCl3): δ 10.08 (bs, 1H), 7.82-7.40 (bm, 2H), 7.35-7.26 (m, 4H), 7.08-6.95 (m, 3H), 5.40 (s, 2H) ppm. HPLC analysis (15:10:75 H2O:A1:MeOH) showed a purity of greater than 99% with a retention time of 4.2 min.

Provenance & Evidence