Ring transformations of heterocyclic compounds. XVII, 2‐(2,4,6‐Triarylphenyl) substituted dihydro‐1H‐imidazolium, dihydrothiazolium and thiazolium salts from 2‐methyl derivatives by pyrylium and thiopyrylium ring transformations

Abstract

AbstractThe synthesis of hitherto unknown 2‐(2,4,6‐triarylphenyl) substituted 4,5‐dihydro‐1H‐imidazolium perchlorates 6, 4,5‐dihydrothiazolium perchlorates 8 and thiazolium perchlorates 9 from their 2‐methyl derivatives 2, 4 and 5, respectively, by a 2,6‐[C5+C] ring transformation of 2,4,6‐triarylpyrylium and ‐thiopyrylium salts 1/10 in ethanol in the presence of an appropriate base (6: sodium ethanolate; 8,9: anhydrous sodium acetate) is reported. Spectroscopic data of the transformation products and structural influences on their formation via anhydrobases of the salts 2, 4 and 5 are discussed.