1,2-Phenylenediamine dihydrochloride → 2-cyclopropyl-1H-1,3-benzodiazole

Participants

Reaction Conditions

Reaction Steps

2-cyclopropanecarboxylic acid (4 g, 52 mmol) was treated with phenylenediamine bis-hydrochloride (1 eq) and polyphosphosphoric acid (52 mL) and heated to 160° C. for 6 h. The reaction was cooled to 0° C. and diluted with water, then basified with NaOH (50% aqueous) until pH>10. The solution was extracted with ethyl acetate, dried (MgSO4), filtered and concentrated, purified by flash chromatography (100% ethyl acetate) giving 2-cyclopropylbenzimidazole (1.1 g, 13%). MS found: (M+H)+=159.

Provenance & Evidence