NEW 2-AMINOTHIAZOLE DERIVATIVE

PURPOSE:To obtain the new derivative useful as a medicine having inhibiting actions on a serine protease, especially the inhibiting actions on an elastase. CONSTITUTION:This compound is expressed by formula I [R1 and R2 are each p-pivaloyloxyphenyl, H, a halogen, an alkyl, a substitutive phenyl, a substitutive benzyl or CH2COOR5 (R5 is H, an alkyl or a substitutive benzyl), with the proviso that at least one is p-pivaloyloxyphenyl; R3 and R4 are each H, an alkyl, an (halo)alkylsulfonyl, a substitutive phenylsulfonyl, amidino, CO-R6 {R6 is an alkyl, a substitutive phenyl, (CH2)m-COOH [(m) is 1-5], (CH2)n-NHR7 [(n) is 1-5; R7 is H, tert-butoxycarbonyl, etc.] or (CH2)Q-R8 (Q is 0-5; R8 is an alkoxy, phenyl, etc.}], e.g. 2-(2-methoxyphenyl)amino-5-methyl-4-(4-pivaloyloxyphenyl) thiazole. The compound is obtained by reacting a compound expressed by formula II with a compound expressed by formula III.