Ethyl chloroformate → CGS 22745

Participants

Reaction Steps

A solution of 12.05 g of (E)-3-[4-(2,5-dimethyl-1H-pyrrol-1-yl)-phenyl]-2-propenoic acid in 350 ml of dichloromethane and 9.7 ml triethylamine, is cooled in an ice bath. To this stirred solution is added 7.0 ml of ethyl chloroformate dropwise. After four hours at ice-bath temperature, 20.7 ml of triethylamine is added, followed by 12.6 g of N-methylhydroxylamine hydrochloride and the mixture is kept at room temperature for 16 hours. This mixture is washed with cold 0.3 N aqueous hydrochloric acid, ice cold sodium bicarbonate and brine. The organic phase is dried over MgSO4, treated with charcoal and filtered. The solvent is evaporated at 50° under reduced pressure and the product is crystallized from ether to give (E)-3-[4-(2,5-dimethyl-1H-pyrrol-1-yl)-phenyl]-N-hydroxy-N-methyl-2-propenamide, m.p. 143°-145°, the compound of formula IV wherein R1 and R2 represent methyl at the 2 and 5 positions, R4 represents methyl, and R3, R8 and R9 represent hydrogen; the compound may also be named (E)-3-[4-(2,5-dimethyl-1H-pyrrol-1-yl)-phenyl]-N-methyl-2-propenohydroxamic acid. The product can also be recrystallized from ethyl acetate (with charcoal and silica gel).

Provenance & Evidence