5-aryl-1H-pyrrole-3-carbonitrile and a pharmaceutical product using the same

A method of producing a compound represented by the formula

• wherein R1 is (1) a C1-6 alkyl group or (2) a phenyl group optionally substituted by 1 substituent selected from the group consisting of (i) a halogen atom, (ii) C1-6 alkyl optionally substituted by 1 to 5 halogens and (iii) C1-6 alkoxy optionally substituted by 1 to 5 halogens, and R2 is a hydrogen atom or a C1-6 alkyl group, or a salt thereof, comprising reducing a compound represented by the formula
• wherein each symbol is as defined above, or a salt thereof using metal hydride or in the presence of a hydrogen source and a metal catalyst, and hydrolyzing the reduced product in the presence of an acid or a base,
• wherein the metal hydride is selected from the group consisting of sodium borohydride, lithium borohydride, zinc borohydride, sodium cyanoborohydride, sodium triacetoxyborohydride, lithium cyanoborohydride, diisobutylaluminum hydride, aluminum hydride, lithium aluminum hydride, borane-THF complex, borane-dimethylsulfide, borane-pyridine and catechol borane;
• the hydrogen source is selected from the group consisting of hydrogen gas, formic acid, ammonium formate, triethylammonium formate, sodium phosphinate and hydrazine;
• the metal catalyst is selected from the group consisting of palladium carbon, palladium hydroxide carbon, palladium oxide, Raney-nickel, platinum oxide, platinum carbon and rhodium carbon;
• the acid is selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, boric acid, formic acid, acetic acid, propionic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and trifluoromethanesulfonic acid;
• and
• the base is selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate and sodium hydrogen carbonate.