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Popa M.M.,Center For Organic Chemistry Cd Nenitzescu | Popa M.M.,Polytechnic University of Bucharest | Georgescu E.,Research Center Oltchim | Caira M.R.,University of Cape Town | And 5 more authors.
Beilstein Journal of Organic Chemistry | Year: 2015

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. © 2015 Popa et al.

Dumitrescu D.G.,Polytechnic University of Bucharest | Dumitrascu F.,Center For Organic Chemistry Cd Nenitzescu | Badea F.,Polytechnic University of Bucharest
UPB Scientific Bulletin, Series B: Chemistry and Materials Science | Year: 2013

Two new helical molecules were prepared using a new protocol consisting of the 1,3-dipolar cycloaddition of isoquinoline and phthalazine dicyanomethylides and 1,2-naphthoquinone as dipolarophile. The corresponding cycloadducts were obtained in good yields and structural confirmation was provided by NMR and IR spectroscopy.

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