| abstract |
A new industrial process for producing compounds of general formula (I) and salts thereof, excellent in the yield and purity of the products, shortened in the process steps, and realized without the intervention of any nitroso compound. In said formula, R1 is lower alkyl, aryl, ar(lower)alkoxyl or heterocyclic group, each of which may be substituted with halogen; and R2 is cyclo(lower)alkyl, aryl or ar(lower)alkyl, each of which may be substituted with halogen. |