6533b833fe1ef96bd129b572

RESEARCH PRODUCT

Unequivocal determination of isomeric products of reaction between 3-methyl-1-phenyl-2-pyrazoline-4,5-dione and aromatic 1,2-diamines

Zdzisław KucybałaRyszard GawineckiErkki KolehmainenAnna KacalaJerzy Paczkowski

subject

chemistry.chemical_compoundHeteronuclear moleculechemistryStereochemistryOrganic ChemistryDrug DiscoveryStructural isomerSubstituentRegioselectivityPyrazolineMultiplicity (chemistry)Biochemistry

description

Abstract Regioselectivity of condensation of 3-methyl-1-phenyl-2-pyrazoline-4,5-dione with aromatic 1,2-diamines is dependent on substituent present. Isomeric 3-methyl-1-phenyl-1H-pyrazolo-[3,4-b]-quinoxaline products are distinguished by comparison of their 2D z-gradient selected 1H, 15N HMBC (Heteronuclear Multiple Bond Correlation) spectra. Multiplicity of H5 signal, which is recognizable by the cross-peak for CH3(3)-N4 and H5-N4 interactions, indicates substitution in position 6 or 7. The applied method is expected to be useful for structure determinations in other positional isomers.

yearjournalcountryeditionlanguage
1999-07-01Tetrahedron
https://doi.org/10.1016/s0040-4020(99)00433-0