Emilian Georgescu

Efficient One-Pot, Three-Component Synthesis of a Library of Pyrrolo[1,2-c]pyrimidine Derivatives

Herein is reported a simple and efficient one-pot three-component synthesis of pyrrolo[1,2-c]pyrimidine derivatives starting from various substituted pyrimidines, 2-bromoacetophenones, and electron deficient alkynes in epoxides acting both as reaction medium and HBr scavanger. This method proved to be very lucrative and avoids formation of ylide inactivation products. The synthesis represents an environmentally benign alternative to classical methods. The new library of compounds was briefly characterized regarding the improved Lipinski rule to asses the potential drug-likeness of the compounds. The majority of compounds are statisfing the Lipinski rule.

Synthesis of Pyrrolo[2,1-a]isoquinolines by Multicomponent 1,3-Dipolar Cycloaddition

Pyrrolo[2,1-a]isoquinoline derivatives were synthesized by one-pot three-component reactions starting from isoquinoline, 2-bromoacetophenones and different non-symmetrical acetylenic dipolarophiles using 1,2-epoxypropane as solvent. The structure of the compounds was assigned by IR and NMR spectroscopy.

Indolizines and pyrrolo(1,2-c)pyrimidines decorated with a pyrimidine and a pyridine unit respectively

Summary The three possible structural isomers of 4-(pyridyl)pyrimidine were employed for the synthesis of new pyrrolo[1,2-c]pyrimidines and new indolizines, by 1,3-dipolar cycloaddition reaction of their corresponding N-ylides generated in situ from their corresponding cycloimmonium bromides. In the case of 4-(3-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine the quaternization reactions occur as expected at the pyridine nitrogen atom leading to pyridinium bromides and consequently to new indolizines via the corresponding pyridinium N-ylides. However, in the case of 4-(2-pyridyl)pyrimidine the steric hindrance directs the reaction to the pyrimidinium N-ylides and, subsequently, to the formation of the pyrrolo[1,2-c]pyrimidines. The new pyrrolo[1,2-c]pyrimidines and the new indolizines were structurally characterized through NMR spectroscopy. The X-ray structures of two of the starting materials, 4-(2-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine, are also reported.

New highlights of the syntheses of pyrrolo(1,2-a)quinoxalin-4-ones

Summary The one-pot three-component reactions of 1-substituted benzimidazoles with ethyl bromoacetate and electron-deficient alkynes, in 1,2-epoxybutane, gave a variety of pyrrolo[1,2-a]quinoxalin-4-ones and pyrrolo[1,2-a]benzimidazoles. The influence of experimental conditions on the course of reaction was investigated. A novel synthetic pathway starting from benzimidazoles unsubstituted at the five membered ring, alkyl bromoacetates and non-symmetrical electron-deficient alkynes in the molar ratio of 1:2:1, in 1,2-epoxybutane at reflux temperature, led directly to pyrrolo[1,2-a]quinoxalin-4-ones in fair yield by an one-pot three-component reaction.

Isoxazole derivatives as new nitric oxide elicitors in plants

Several 3,5-disubstituted isoxazoles were obtained in good yields by regiospecific 1,3-dipolar cycloaddition reactions between aromatic nitrile oxides, generated in situ from the corresponding hydroxyimidoyl chlorides, with non-symmetrical activated alkynes in the presence of catalytic amounts of copper(I) iodide. Effects of 3,5-disubstituted isoxazoles on nitric oxide and reactive oxygen species generation in Arabidopsis tissues was studied using specific diaminofluoresceine dyes as fluorescence indicators.

Fast and Green One-Pot Multicomponent Synthesis of a Library of Pyrrolo[1,2-c] Pyrimidines Under Microwave Irradiation

A simple, clean and rapid one-pot three component, microwave-assisted synthesis of pyrrolo[1,2-c]pyrimidine derivatives starting from various substituted pyrimidines, 2-bromoacetophenones and nonsymmetrical, electron deficient alkynes in 1,2-epoxybutane which acts both as solvent and acid scavenger is reported. This one-pot three component synthesis implies short reaction times being at the same time highly cost-effective and environmental friendly.

New Strigolactone Mimics as Exogenous Signals for Rhizosphere Organisms

The importance of strigolactones in plant biology prompted us to synthesize simplified strigolactone mimics effective as exogenous signals for rhizosphere organisms. New strigolactone mimics easily derived from simple and available starting materials in significant amounts were prepared and fully characterized. These compounds contain an aromatic or heterocyclic ring, usually present in various bioactive molecules, connected by an ether link to a furan-2-one moiety. The new synthesized strigolactone mimics were confirmed to be active on plant pathogenic fungi and parasitic weed seeds.

Coumarin substituted pyrrolo-fused heterocyclic systems by 1,3-dipolar cycloadditon reactions

A variety of new pyrrolo-fused heterocyclic systems bearing a 3-carbonylchromen-2-one moiety on the pyrrole rings was obtained based on 1,3-dipolar cycloaddition reactions of corresponding cycloimmonium-ylides, generated in situ from the quaternary salts of several N-heterocycles with 3-(2-bromoacetyl)-2H-chromen-2-one, with electron-deficient alkynes. The synthetic strategies were both one-pot, three-component and classical multistep 1,3-dipolar cycloaddition reactions. The all newly synthesized compounds were structurally characterized by elemental analysis, IR and NMR spectroscopy.Graphical abstract

Schiff bases containing a furoxan moiety as potential nitric oxide donors in plant tissues

Stable Schiff bases containing a furoxan moiety are synthesized as single regioisomers by the reaction of 3-methyl-2-oxy-furazan-4-carbaldehydewith various amino compounds at room temperature. The structures of synthesized compounds were fully characterized by multinuclear NMR spectroscopy and X-ray crystallography. The effect of synthesized Schiff bases containing a furoxan moiety on biological generation of reactive oxygen species and nitric oxide in plant tissues was investigated for the first time by fluorescence microscopy and the released NO identified as nitrite with Griess reagent. There is a good correlation between the biological generation of NO determined by fluorescence microscopy and with Griess reagent. Some of the synthesized compounds exhibited both nitric oxide and reactive oxygen species generation abilities and represent potential NO donors in plant tissues.

1-Naphthoyl-pyrrolo[1,2-a]quinolines from Quinolinium N-Ylides.

A variety of the title compounds (IV) (10 examples) is synthesized by 1,3-dipolar cycloaddition of quinolinium N-ylides generated in situ by a simple one-pot, three-component reaction.