PRODUCTION OF THIAZOLINE DERIVATIVE

PROBLEM TO BE SOLVED: To effectively obtain a thiazoline derivative useful for medicines for treating diabetic complications, etc., in a high purity and a high yield by reacting a specific N-substituted maleimide compound with a specific thiosemicarbazone compound. SOLUTION: An N-substituted maleimide compound of formula I (R is a substituted phenyl, a lower alkyl, a phenyl lower alkyl) such as N- phenylmaleimide is reacted with a thiosemicarbazone compound of formula II [R is N=R (R is a lower alkylidene)] such as acetone thiosemicarbazone to obtain a thiazoline derivative of formula III.