O-Phenylenediamine → Ethyl 4-(benzimidazol-2-yl)-3,3-dimethylbutanoate

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Reaction Conditions

Reaction Steps

A solution of 139.2 g of the acid chloride ethyl ester of 3,3-dimethylglutaric acid, prepared in Example 28, in 125 ml of chloroform, stabilized with amylene, is added dropwise, at a temperature of between 5° C. and 10° C., to a solution of 72.8 g of orthophenylenediamine and 112 ml of triethylamine in 1 l of anhydrous tetrahydrofuran. The mixture is stirred at 0° C. for two hours and then at 50° C. for one hour; the crystals are filtered off and the solvents are evaporated off under vacuum. The residue is taken up in 4.4 l of ethanol and 444 l of concentrated hydrochloric acid and the mixture is refluxed for 12 hours. The solvents are evaporated off and the residue is taken up with water and then neutralized with a 1N solution of sodium hydroxide and extracted with ether. The ether phase is dried and then evaporated under vacuum to give 99 g of ethyl 4-(benzimidazol-2-yl)-3,3-dimethylbutanoate in the form of crystals melting at 123° C.

Provenance & Evidence