| abstract |
A new industrial process excellent in yield and purity for preparing a compound of the formula: <CHEM> or a salt thereof in a less number of steps with a synthetic pathway without proceeding via nitroso compounds, wherein R<1> is lower alkyl, aryl, ar(lower)alkoxy or heterocyclic group, each of which may be substituted with halogen, and R<2> is cyclo(lower)alkyl, aryl or ar(lower)alkyl, each of which may be substituted with halogen. |