S. V. Verin

2-benzopyrylium salts. 45. Interaction of 2-benzopyrylium salts and their monocyclic analogs with imines of ketones

It was shown that ketonimines, which can have imine--enamine tautomerism, react with pyrylium salts in the enamined form. In such reactions, the 2-benzopyrylium salts are transformed into unsaturated ketones, and their monocyclic analogs are transformed into either quinolizinium salts or pyridinium salts depending on the structure of the initial imine.

Dimerization reactions of 2-benzopyrylium salts (review)

Data on asymmetric dimerization reactions of 2-benzopyrylium salts and conversions of the resulting dimers are summarized.

2-Benzopyrylium salts.: 40. Addition of azomethines to 2-benzopyrylium salts ? New method for the synthesis of isoquinolinium systems

The addition of azomethines to 2-benzopyrylium salts, which leads to derivatives of 3,4-dihydroisoquinolinium salts, was observed. An assumption regarding the mechanism of the reaction is expressed on the basis of its stereoselectivity. Dehydrogenation of the compounds obtained to completely aromatic isoquinolinium salts and reduction to tetrahydroisoquinolines were realized.

2-Benzopyrylium salts. 43. Conversion of dimers of 2-benzopyrylium salts to benzofuran derivatives

In the acid-catalyzed interaction of dimers of 2-benzopyrylium salts with peracetic acid and hydrogen peroxide, the oxidation products that are formed are readily converted to benzofuran derivatives.

2-Benzopyrylium salts. 42. Ortho-quinoid intermediates in recyclization reactions of 2-benzopyrylium salts

The interaction of 1-styryl-substituted 2-benzopyrylium salts with morpholine, methylamine, and malononitrile is highly stereoselective informing cis-3,4-dihydronaphthalenes; this can be taken as evidence that ortho-quinoid intermediates participate in these conversions.

2-Benzopyrylium salts. 41. Intramolecular transformations of 4-1′-dimers of α-unsubstituted 2-benzopyrylium salts

Recyclization reactions of 4-1′-dimers of 2-benzopyrylium salts leading to naphthalene derivatives are described. A new variant of the intramolecular Cannizzaro rearrangement has been discovered.