2-BENZOPYRYLIUM SALTS. 44. FORMATION OF 4-ACYL-3,4-DIHYDROISOQUINOLINIUM SALTS FROM THE REACTION OF 2-BENZOPYRYLIUM SALTS WITH AZOMETHINES AND THE CYCLOADDITION OF MALEIMIDES TO THE PRODUCT OF THEIR DEPROTONATION, THE 2,3-DIHYDROISOQUINOLINES

Article abstract of DOI:10.1007/BF00532071

The effect of substituents in the 2-benzopyrylium cation and in the azomethines on the character of their reaction in various solvents has been clarified. It was shown that the 4-acyl-3,4-dihydroisoquinolinium salts resulting after deprotonation form compounds with an ortho-quinonoid structure which then react with maleimides by cycloaddition.