Search results for "Pyrimidine"

Spin Polarization and Ferromagnetism in Two-Dimensional Sheetlike Cobalt(II) Polymers: [Co(L)2(NCS)2] (L=Pyrimidine or Pyrazine)

1998

Efficient synthesis of novel pyrido[3,2-d]pyrimidine-2,4-diones

2003

Abstract A series of pyrido[3,2- d ]pyrimidine-2,4-diones 5a – g have been synthesized through conversion of 2,3-pyridinedicarboxylic anhydride 1 into half-ester 2 , subsequent Curtius rearrangement and further reaction with amino acids.

Heterocyclic rearrangements. Synthesis of 1,2,4-oxadiazolo[2,3-a]pyrimidinium systems and their ring opening into pyrimidineN-oxides

1986

Reaction des methyl- et phenyl-5 amino-3 oxadiazoles-1,2,4 avec l'acetylacetone ou la benzoylacetone en presence d'acide perchlorique: obtention de methyl- et phenyl-2 methyl- et phenyl-5 methyl-7 oxadiazolo [2,3-a] pyrimidiniums-4 qui se decyclisent ensuite en oxydes-1 d'acylamino-2- et amino-2 methyl-4 methyl- et phenyl-6 pyrimidines

Synthesis of 4-amino-5-fluoropyrimidines and 5-amino-4-fluoropyrazoles from a β-fluoroenolate salt

2020

A synthesis of fluorinated pyrimidines under mild conditions from amidine hydrochlorides and the recently described potassium 2-cyano-2-fluoroethenolate was developed. A broad substrate scope was tested and mostly excellent yields were obtained. The synthesis of fluorinated aminopyrazoles from the same fluorinated precursor could be demonstrated but proceeded with lower efficiency.

Synthesis of pyrido[2,3-d]pyrimidines in the reaction of 6-amino-2,3-dihydro-2-thioxo-4(1H)-pyrimidinone with chalcones

1992

6-Amino-2,3-dihydro-2-thioxo-4(1H)-pyrimidinone (1) reacts in boiling DMF with α,/β-unsaturated ketones 2 yielding the pyrido[2,3-d]pyrimidine systems 5 and 6, respectively. The orientation in the addition process can be determined by nmr measurements, especially by NOE difference spectroscopy. The products do not correspond to a normal Skraup or Doebner-v. Miller synthesis.

ChemInform Abstract: Cyclocondensation of 6-Acetyl-4,7-dihydro-5-methyl-7-phenyl[1,2,4]triazolo[1,5-a]pyrimidine with Hydroxylamine and Hydrazine.

2010

The cyclocondensation of 6-acetyl-4,7-dihydro-5-methyl-7-phenyl[1,2,4]triazolo[1,5-a]pyrimidine (3) with hydroxylamine or hydrazine leads to 3a,4,9,9a-tetrahydro-3,9a-dimethyl-4-phenylisoxazolo-[5,4-d][1,2,4]triazolo[1,5-a]pyrimidine (4a) and 3a,4,9,9a-tetrahydro-3,9a-dimethyl-4-phenyl-1H-pyrazolo[3,4-d][1,2,4]triazolo[1,5-a]pyrimidine (4b), respectively. In the presence of methanolic hydrogen chloride, 4b undergoes a cleavage of the pyrimidine ring to yield (5-amino-1,2,4-triazol-1-yl)(3,5-dimethylpyrazol-4-yl)phenylmethane (5). The structure determination of the compounds obtained is based on 1H and 13C nmr spectra including NOE measurements.

Cyclocondensation of 6-acetyl-4,7-dihydro-5-methyl-7-phenyl[1,2,4]triazolo[1,5-a]pyrimidine with hydroxylamine and hydrazine

1998

The cyclocondensation of 6-acetyl-4,7-dihydro-5-methyl-7-phenyl[1,2,4]triazolo[1,5-a]pyrimidine (3) with hydroxylamine or hydrazine leads to 3a,4,9,9a-tetrahydro-3,9a-dimethyl-4-phenylisoxazolo-[5,4-d][1,2,4]triazolo[1,5-a]pyrimidine (4a) and 3a,4,9,9a-tetrahydro-3,9a-dimethyl-4-phenyl-1H-pyrazolo[3,4-d][1,2,4]triazolo[1,5-a]pyrimidine (4b), respectively. In the presence of methanolic hydrogen chloride, 4b undergoes a cleavage of the pyrimidine ring to yield (5-amino-1,2,4-triazol-1-yl)(3,5-dimethylpyrazol-4-yl)phenylmethane (5). The structure determination of the compounds obtained is based on 1H and 13C nmr spectra including NOE measurements.

The chemistry of [1,2,3]triazolo[1,5- c ]pyrimidine

2001

Abstract Reactions of [1,2,3]triazolo[1,5-c]pyrimidine 2 with some electrophiles and nucleophiles are reported. Triazole ring opening and loss of nitrogen is the principal reaction with electrophiles. With strong acids protonation on N6 competes successfully. Derivatives in which the pyrimidine ring has been opened are obtained in reactions with nucleophiles. No stable simple substitution compounds were found.

ChemInform Abstract: Pyrazolo[3,4-d]pyrimidine Derivatives as COX-2 Selective Inhibitors: Synthesis and Molecular Modelling Studies.

2009

The pyrazolo[3,4-d]pyrimidine system shows a multitude of interesting pharmacological properties. Owing to the potential anti-inflammatory activity of 5-benzamido-pyrazolo[3,4-d]pyrimidin-4-one derivatives and considering the easy synthesis of this class of compounds, a set of new 5-benzamido-1H-pyrazolo[3,4-d]pyrimidin-4-ones has been prepared in 42-80% yields by reacting 5-aminopyrazole-4(N-benzoyl)carbohydrazide derivatives and the opportune triethylorthoesters. Compounds 8a, b, 10a-d, and 11a, b revealed a superior inhibitory profile against COX-2, when compared to that of reference standards NS398 and indomethacin. Molecular modelling studies confirmed the obtained biological results.

Antidiabetische wirkstoffe. III. 4,5,6-Trisubstituierte 2-(4-toluidino)pyrimidine

1984

Aus der Kondensation von 4-Tolylguanidin (1) mit den β-Diketonen 2a-b gehen die 2-(4-Toluidino)pyrimidine 3a-b hervor. The condensation of 4-tolyiguanidine (1) with the β-kiketones 2a-b yields the 2-(4-toluidino)pyrimidines 3a-b.