title: Diversity Oriented Synthesis of Polycyclic Heterocycles through the Condensation of 2-Amino[1,2,4]triazolo[1,5-a]pyrimidines with 1,3-Diketones.
abstract: The acid-catalyzed condensation between 2-aminosubstituted [1,2,4]triazolo[1,5-a]pyrimidines and their analogues with various saturation of the pyrimidine ring and 1,3-diketones or 1,1,3,3-tetramethoxypropane was evaluated as a new approach for the synthesis of diversely substituted polycyclic derivatives of triazolopyrimidine. The reaction of 4,5,6,7-tetrahydro- or aromatic aminotriazolopyrimidines results in selective formation of the corresponding [1,2,4]triazolo[1,5-a:4,3-a']dipyrimidin-5-ium salts, and the condensation of substrates containing the 4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine fragment is accompanied by a cascade rearrangement with unusual recyclization of the dihydropyrimidine ring to yield partially hydrogenated [1,2,4]triazolo[1,5-a:4,3-a']dipyrimidin-5-ium or pyrimido[1',2':1,5][1,2,4]triazolo[3,4-b]quinazolin-5-ium salts. The proposed methodology exhibits a wide scope, providing rapid access to polycondensed derivatives of the [1,2,4]triazolo[1,5-a]pyrimidine scaffold. DFT calculations of the Gibbs free energies of possible isomers were performed to rationalize the experimentally observed reactivity and selectivity.
authors.affiliation: Platov South-Russian State Polytechnic University (NPI) , Prosveschenya 132, 346428 Novocherkassk, Russian Federation.
authors.forename: Dmitry A
authors.initials: DA
authors.lastname: Pyatakov
authors.affiliation: Platov South-Russian State Polytechnic University (NPI) , Prosveschenya 132, 346428 Novocherkassk, Russian Federation.
authors.forename: Andrey N
authors.initials: AN
authors.lastname: Sokolov
authors.affiliation: Platov South-Russian State Polytechnic University (NPI) , Prosveschenya 132, 346428 Novocherkassk, Russian Federation.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Astakhov
authors.affiliation: Platov South-Russian State Polytechnic University (NPI) , Prosveschenya 132, 346428 Novocherkassk, Russian Federation.
authors.forename: Andrey Yu
authors.initials: AY
authors.lastname: Chernenko
authors.affiliation: Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences , Leninsky Prospect 47, Moscow 119991, Russian Federation.
authors.forename: Artem N
authors.initials: AN
authors.lastname: Fakhrutdinov
authors.affiliation: M. V. Lomonosov Moscow State University , Leninskie Gory 1-3, Moscow, 119991, Russian Federation.
authors.forename: Victor B
authors.initials: VB
authors.lastname: Rybakov
authors.affiliation: M. V. Lomonosov Moscow State University , Leninskie Gory 1-3, Moscow, 119991, Russian Federation.|A. N. Frumkin Institute of Physical Chemistry and Electrochemistry RAS , Leninsky prospect 31, Moscow 119071, Russian Federation.
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Chernyshev
authors.affiliation: Platov South-Russian State Polytechnic University (NPI) , Prosveschenya 132, 346428 Novocherkassk, Russian Federation.
authors.forename: Victor M
authors.initials: VM
authors.lastname: Chernyshev