Regioselective synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles

An efficient and simple method for the synthesis of 2-unsubstituted 1-aryl-4- and 1-aryl-5-acylimidazoles has been developed. It consists in the condensation of α-diketone monooximes with aromatic amines and formaldehyde on the presence of boron trifluoride etherate, leading to the formation of stable boron trifluoride complexes of N-oxides. Further reduction of these complexes led to the corresponding imidazoles. This method permits broad variations of substituents in the aryl part of these compounds.     

Synthesis of novel 4<Emphasis Type="Italic">H</Emphasis>-furo[3,2-c]pyran-4-ones and 4<Emphasis Type="Italic">H</Emphasis>-furo[3,2-<Emphasis Type="Italic">c</Emphasis>]chromen-4-ones

It was found that the condensation of two equivalents of 4-hydroxy-6-methyl-2H-pyran-2-one or 4-hydroxycoumarin with arylglyoxals in boiling formic acid leads to 4H-furo[3,2-c]-pyran-4-ones or 4H-furo[3,2-c]chromen-4-ones, respectively.     

Amine curing agents based on 4,4′-methylene bisaniline for epoxy binders

The published data on the synthesis of 4,4′-methylene bisanilines used as aromatic amine curing agents for epoxy resins have been analyzed. A most promising technological process for their preparation that can be applied to the synthesis of various derivatives is found. It consists in condensing the corresponding anilines with formaldehyde in the presence of an acid catalyst.     

Synthesis of Substituted Imidazo[1,2-a]Pyridin-3-yl-Acetic Acids by Multicomponent Condensation of 2-Aminopyridines with Arylglyoxals and Meldrum’s Acid

Chemistry of Heterocyclic Compounds - A simple and effective method for the synthesis of substituted imidazo[1,2-a]pyridin-3-yl-acetic acids has been developed based on the multicomponent...     

Ultraviolet irradiation of terarylenes: A facile,efficient, and environmentally friendly method for the synthesis of fused polycyclic products

Ultraviolet irradiation of hydroxyl substituted terarylenes provided a simple, efficient, and environmentally friendly method for the synthesis of imidazo[1,2-a]pyridines. The starting terarylenes were prepared via the one-pot, three-component condensation of readily accessible arylglyoxals, 2-aminopyridines, and dimedone.     

A new facile method for the synthesis of 3-imidazolylpropionic acid N-oxides

Chemistry of Heterocyclic Compounds - A facile and efficient method for the preparation of 3-imidazolylpropionic acid N-oxides has been developed. It involves condensation of 2-unsubstituted...     

Condensation of 5-hydroxy-2-methyl-4<Emphasis Type="Italic">H</Emphasis>-pyran-4-one with arylglyoxals. Synthesis and properties of 2-aryl-1-(3-hydroxy-6-methyl-4-oxo-4<Emphasis Type="Italic">H</Emphasis>-pyran-2-yl)ethane-1,2-diones

A convenient method was developed for the synthesis of previously unknown 1,2-diketones, based on the condensation of 5-hydroxy-2-methyl-4H-pyran-4-one with arylglyoxals. The study demonstrated the possibility of using these compounds to synthesize nitrogen-containing hetero cyclic systems bearing the 3-hydroxypyran-4-one moiety.     

Synthesis of substituted benzofurans by condensation of arylglyoxals with enols and phenols

A convenient method for the synthesis of previously unknown substituted 3-hydroxy-5,5- dimethyl-2-(2-arylbenzofuran-3-yl)cyclohex-2-enones, 4-hydroxy-6-methyl-3-(2-arylbenzofuran- 3-yl)-2H-pyran-2-ones, and 2-hydroxy-3-(2-arylbenzofuran-3-yl) naphthoquinones was developed based on the reaction of 3,4-methylenedioxyphenol or 2-naphthol with pyridinium salts obtained by multicomponent condensation of arylglyoxals with carbo- or heterocyclic enols and 4-dimethylaminopyridine.