Journal of Molecular Liquids
Efficient synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives
using succinimidinium N-sulfonic acid hydrogen sulfate as a new ionic
liquid catalyst
⁎
⁎
Masoumeh Abedini , Farhad Shirini , Javad Mohammad-Alinejad Omran
Department of Chemistry, College of Science, University of Guilan, Rasht, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 13 June 2015
Received in revised form 7 September 2015
Accepted 9 September 2015
Available online xxxx
Succinimidinium N-sulfonic acid hydrogen sulfate is prepared as a new ionic liquid and characterized with a va-
riety of techniques including FT-IR, 1H and 13C NMR, SEM, mass spectra method as well as Hammett acidity func-
tion. After identification, this reagent was used as an efficient catalyst for the multi-component synthesis of 2H-
indazolo[2,1-b]phthalazine-trione derivatives. The simple work-up, mild reaction conditions, excellent yields
and relatively short reaction times are the notable advantages of this protocol. In addition, the ionic liquid
could be recycled several times without appreciable reduction in its catalytic activity.
Keywords:
© 2015 Elsevier B.V. All rights reserved.
Succinimidinium N-sulfonic acid hydrogen
sulfate
Ionic liquid
2H-indazolo[2,1-b]phthalazine-trione
Aldehyde
1. Introduction
reported in the literature [10–20]. However, some of these methods
suffer from limitations such as the use of expensive catalysts, harsh
Ionic liquids (ILs) have received considerable interest as eco-friendly
solvents, catalysts and reagents in green synthesis. This interest can be
attributed to their unique properties such as negligible vapor pressure,
nonflammability, nomiscibility with nonpolar solvents, reasonable
thermal and chemical stability and reusability for many times without
considerable decrease in their activity [1]. Among these types of com-
pounds, acidic ionic liquids are the most important ones which have
been successfully used in different types of organic transformations [2].
In the past decade, other types of acidic ionic liquids based on N-
substituted reagents are prepared and successfully used for the acceler-
ation of some of the organic reactions including functional group trans-
formation reactions and synthesis of the various types of organic
compounds via the multi-component reactions [3].
reaction conditions, the use of toxic solvents, low yields and long re-
action times. Therefore, it is important to find more efficient catalysts
and methods for the synthesis of these types of compounds.
In recent years, the use of green catalysts or conditions in synthetic
reactions attracted the attention of many organic chemists. This atten-
tion can be attributed to the reduction of environmental pollution and
the cost of the applied methods. Therefore, preparation of phthalazine
derivatives in the presence of green catalysts such as ionic liquids or
heterogeneous compounds in the absence of solvent is a useful direction
in green chemistry [21–25].
In 2011, and on the basis of our previous reports using ionic liquids in
organic transformations [26], we have introduced succinimide-N-sulfonic
acid [SuSA] for the promotion of different types of organic reactions [27].
Herein and in continuation of these studies we wish to report the
preparation, characterization and application of succinimidinium N-
sulfonic acid hydrogen sulfate {[SuSA-H]HSO4} in the promotion of the
synthesis of 2H-indazolo[2,1-b]phthalazine-trione derivatives.
Synthesis of heterocycles containing phthalazine is of interest because
of their very important pharmacological and biological activities such as
anti-inflammatory [4], anti-convulsant [5], anti-microbial [6], anti-fungal
[7] and anti-cancer [8] activities. In addition, these compounds can be
used as new luminescent materials or fluorescence probes [9].
Among these compounds, the synthesis of 2H-indazolo[2,1-
b]phthalazine-trione derivatives is so attracted the attention of
many organic chemists that in the past decade, several reports on
the synthesis of them using different types of catalysts have been
2. Experimental
2.1. General
Chemicals were purchased from Fluka, Merck, and Aldrich chemical
companies. All yields refer to the isolated products. Products were
⁎
Corresponding authors.
0167-7322/© 2015 Elsevier B.V. All rights reserved.