Abstract
Three series of 3,7-bis(arylazo)-2,6-dimethyl-1H-imidazo[1,2-b]pyrazoles were prepared starting from N-aryl-2-oxo-propanehydrazonoyl chlorides. The acid dissociation constants pKa were determined and correlated with the Hammett equation. The results of such correlations together with the spectroscopic data indicated that the title compounds exist predominantly in the 1H-bis(arylazo) form.
References
1.
Blass
B.F.
,
Srivastava
A.
,
Coburn
K.R.
,
Faulkner
A.L.
,
Janusz
J.J.
,
Ridgeway
J.M.
, and
Seibel
W.L.
, Tetrahedron Lett. , 2004 , 45 , 619 .
2.
Bruno
O.
,
Brullo
C.
,
Bondavalli
F.
,
Ranise
A.
,
Schenone
S.
,
Falzarano
M.S.
,
Varani
K.
, and
Spisani
S.
, Bioorg. Med. Chem. Lett. , 2007 , 17 , 3696 .
3.
Raposo
M.M.M.
,
Sousa
A.M.R.
,
Fonseca
A.M.C.
, and
Kirsch
G.
, Tetrahedron , 2005 , 61 , 8249 .
4.
Habibi
M.H.
,
Hassanzadeh
A.
, and
Zeini-Isfahani
A.
, Dyes Pigm. , 2006 , 69 , 93 .
5.
Shawali
A.S.
, and
Mosselhi
M.A.N.
, J. Heterocycl. Chem. 2003 , 40 , 725 .
6.
Aggarwal
R.
,
Kumar
V.
,
Kumar
R.
, and
Singh
S.P.
, Beil. J. Org. Chem. , 2011 , 7 , 179 .
7.
Shawali
A.S.
,
Mosselhi
M.A.N.
,
Altablawy
F.M.A.
,
Farghaly
T.A.
, and
Tawfik
N.M.
, Tetrahedron , 2008 , 64 , 5524 .
8.
Shawali
A.S.
,
Abdelkader
M.H.
, and
Altablawy
F.M.A.
, Tetrahedron , 2002 , 58 , 2875 .
9.
Shawali
A.S.
,
Mosselhi
M.A.N.
,
Farghaly
T.A.
,
Shehata
M.R.
, and
Tawfik
N.M.
, J. Chem. Res. , 2008 , 452 .
10.
Holtzwart
R.
, J. Prakt. Chem. , 1886 , 39 , 230 .
11.
Hirsch
V.E.
, Liebigs Ann. Chem. , 1965 , 690 , 33 .
12.
Shawali
A.S.
,
Harb
N.M.S.
, and
Badahdah
K.O.
, J. Heterocycl. Chem. , 1985 , 22 , 1397 .
13.
Shawali
A.S.
, and
EL-Sheikh
S.
, J. Heterocycl. Chem. , 2003 , 40 , 207 .
14.
Shawali
A.S.
, and
Farghaly
T.A.
, Tetrahedron , 2004 , 60 , 3051 .
15.
Diekmann
W.
, and
Platz
O.
, Chem. Ber. , 1906 , 38 , 2989 .
16.
Eweiss
N.F.
, and
Osman
A.
, J. Heterocycl. Chem. , 1980 , 17 , 713 .
17.
Mosselhi
M.A.N.
,
Abdallah
M.A.
,
Mohamed
Y.F.
, and
Shawali
A.S.
, Phosphorus, Sulfur Silicon , 2002 , 177 , 487 .
18.
Jollimore
J.V.
,
Vacheresse
M.
, and
Vaughan
K.
, Can. J. Chem. , 1996 , 74 , 254 .
19.
Brown
D.S.
,
Jollimore
J.V.
,
Merrin
M.P.
,
Vaughan
K.
, and
Hooper
D.L.
Can. J. Chem. , 1995 , 73 , 169 .
20.
Draber
W.
,
Buchel
K.H.
, and
Schafer
G.
, Zeit. Natuforsch. (B) , 1972 , 27 , 159 .
21.
Van Uitert
L.G.
, and
Haas
C.J.
, J. Am. Chem. Soc. , 1953 , 75 , 451 .
22.
Gans
P.
,
Sabatini
A.
, and
Vacca
A.
, Inorg. Chim. Acta , 1976 , 18 , 237 .