3-methyl-1-phenyl-1h-pyrazolo[3,4- b]quinoxalines: mass spectral

XVII-th ARS SEPARATORIA – Borówno, Poland 2002
3-METHYL-1-PHENYL-1H-PYRAZOLO[3,4B]QUINOXALINES: MASS SPECTRAL STUDIES OF NEW
BIDENTATE LIGANDS
Andrzej J. GORĄCZKO, Zdzisław KUCYBAŁA and Jerzy PĄCZKOWSKI
University of Technology and Agriculture, Bydgoszcz, Poland
e-mail: [email protected]
Study on synthesis of this type ligands has proofed the presence of 1,3dihydro-3'-methyl-1'-phenylspiro[2H-imidazole-2-4'-pyrazole]-5'(1H)-one
(B) as the intermediate, obtained from 3-methyl-1phenyl-2-pyrazoline-4,5dione (A) and aromatic amines. This intermediate can be transferred to the
final product (C) by heating with acetic acid [1].
H3C
N
H2N
R1 EtOH
H2N
R2
+
N
H
N
H3C
O
O
N
∆
H3C
R1
CH3COOH
N
O
N
H
R2
∆
N
N
R1
N
R2
(C)
(B)
(A)
N
More recently Kucybała et al. [2] analysed the selectivity of this reaction and
described the bidentate ligand properties [3].
H3C
N
RI
N
R II
N
N
3-methyl-1-phenyl-1H-pyrazolo[3,4-b]quinoxalines
RI
H
H
CH3
Cl
H
Cl
H
NO2
RII
H
CH3
H
H
Cl
Cl
NO2
H
Analysis of the experimental data allows developing the fragmentation
pathways scheme for the compounds.
The experimental mass spectra suggest a presence of two main types of ions:
ions related to unsubstituted 3-methyl-1-phe-nyl-pyrazolo[3,4-b]-quinoxaline and other ones that correspond to the presence of the functional groups at
the position 6- and/or 7- and ions that arise from the fragmentation process.
The molecules of 3-methyl-1-phenyl-1H-pyrazolo[3,4-b] quinoxalines are
very stable, and fragmentation ions, which are observed in fragmentation,
XVII-th ARS SEPARATORIA – Borówno, Poland 2002
characterized of aromatic structure. The benzo[4,5]imid-azol[1,2-a]quinoxaline skeleton is a crucial element of the pyrazolo[3,4-b]quinoxalines
fragmentation.
CH 3
N
RI
N
N
N
RI
N
RII
-
RI
N
RII
N
-CN
RI
N
-
+.
(76)
N
N
(90)
M-68
RII
M
N
M-41
RI
N
M-15
-CHN
N
N
N
RII
N
-CN
N
-CH3
RI
HN
RI
RII
N
M-117
N
RII
M-131
RII
M-94
1. Metwally S.A.M., Atta F.M., Abd El-Monem M.E., 1995, Indian J. Chem. 34B (3), 248
2. Kolehmainen E., Kucybała Z., Gawinecki R., Pączkowski J., Kacała A., 1999,
Tetrahedron 55, 8475
3. Kucybała, Z., Pietrzak, M., Grzona, I., Pączkowski, J., 1998, 17th IUPAC Symphosium on
Photochemistry, Sitges (Spain) (PB-56)