Synthesis of substituted naphtho[1,2-b]benzofuran-7(8H)-ones via photoinduced rearrangement of 4H-chromen-4-one derivatives.

A simple and efficient method was developed for the synthesis of substituted naphtho[1,2-b]benzofuran-7(8H)-ones based on the photorearrangement reaction of 4H-chromen-4-one derivatives. The studied reaction includes the photocyclization of the hexatriene system, [1,9]-H-sigmatropic rearrangement and heterocyclic ring opening. The starting terarylenes were prepared via a new three-component tandem condensation of 3-(dimethylamino)-1-(2-hydroxyaryl)prop-2-en-1-ones, arylglyoxals and cyclic 1,3-diketones.

Photolysis of 3-(1-acyl-5-aryl-3-pyrazolinyl)coumarins-Effective Fluorescence Decay.

Photophysical characteristics of new 3-(1-acyl-5-aryl-3-pyrazolinyl)coumarins have been measured. These coumarin derivatives are found to be effective fluorophores and show high values of quantum yields of fluorescence both in nonpolar and in polar solvents. The 3-(1-acyl-5-aryl-3-pyrazolinyl)coumarins turned to be photosensitive compounds and undergo photolysis under irradiation in the range of 310-465 nm. Photolysis is suggested to include retro-cyclization and retro-condensation steps. The process is accompanied by a sharp drop of fluorescence that can be of interest for the creation of new media in optical recording of information.

One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines.

The condensation of primary amines with N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamides was explored. Thus, a previously unknown recyclization of the starting material was observed in acidic ethanol in the presence of an amine, which provided the corresponding dihydropyrrolone derivative as the major reaction product. Based on this transformation, a practical and convenient one-pot synthetic method for substituted pyrrolo[3,4-b]pyridin-5-ones could be devised.