Synthesis of polybenzoquinazolines via an intramolecular dehydration of photocyclization

Synthesis of substituted 8H-benzo[h]pyrano[2,3-f]quinazolin-8-ones via photochemical 6π-electrocyclization of pyrimidines containing an allomaltol fragment

For the first time, we elaborated a method for the synthesis of pyrimidines containing an allomaltol unit. The suggested approach is based on the reaction of 2-(1-(dimethylamino)-3-oxo-3-arylprop-1-en-2-yl)-3-hydroxy-6-methyl-4H-pyran-4-ones with cyanamide. The photochemical behavior of the obtained pyrimidines was investigated. It was shown that for the hydroxy derivatives the main pathway of phototransformation is a 6π-electrocyclization of the 1,3,5-hexatriene system and subsequent [1,9]-H sigmatropic shift leading to dihydrobenzo[h]pyrano[2,3-f]quinazolines. At the same time, for methylated analogues the photoreaction proceeds in two directions resulting in the formation of a mixture of the corresponding dihydrobenzo[h]pyrano[2,3-f]quinazolines and polyaromatic products. The obtained dihydro derivatives are stable compounds and do not undergo aromatization upon further UV irradiation. The structures of two of the dihydrobenzo[h]pyrano[2,3-f]quinazolines were confirmed by X-ray diffraction analysis. Based on the performed studies, a two-stage telescopic method for the synthesis of polyaromatic benzo[h]pyrano[2,3-f]quinazolines including the initial photocyclization of the starting pyrimidines and the final dehydration was proposed.

N-Aryl glycines as versatile initiators for various polymerizations

N-(1-Pyrenyl)glycine can act as a versatile initiator for various polymerizations.

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.

Synthesis of (2-hydroxyphenyl)(fusedphenyl)methanones via the photo-induced rearrangement of 2′-arylisoflavones

The photo-induced rearrangement of 2′-arylisoflavones (aryl = phenyl, 1-naphenyl, and 2-naphenyl) for the synthesis of (2-hydroxyphenyl)(fusedphenyl)methanones in EtOH under Ar at room temperature has been developed.

Synthesis of Polycyclic Heteroaromatic Coumarins via Photoinduced Dehydrogenative Annulation of 4-Phenyl-3-heteroarylcoumarins

An efficient, oxidant and metal-free synthesis of polycyclic heteroaromatic coumarins was developed. H-Furo[2',3':3,4]naphtho[2,1-c]chromen-4-one (2a-2f), 1H-benzofuro[2',3':3,4]naphtho[2,1-c]chromen-1-one (2g-2j), and 4H-thieno[2',3':3,4]naphtho[2,1-c]chromen-4-one (2k-2s) derivatives were obtained by the irradiation of 4-phenyl-3-heteroarylcoumarin in EtOH-H₂O (9:1, v/v) using a high-pressure Hg lamp as the light source, at room temperature and under an Ar atmosphere. Owing to the expansion of the π-conjugation system, 2a-2s showed strong fluorescence emissions in ethanol solution ( Φ_F = 0.40-0.83).

Annulation of 2,3-diphenyl-4H-chromen-4-ones via photo-induced hydrogen evolution

An efficient photo-induced direct intermolecular hydrogen evolution and annulation of 2,3-diphenyl-4H-chromen-4-ones in EtOH–H₂O (19 : 1, v/v) at room temperature is described, which eliminates the use of any catalysts, oxidants and additives.