Silica gel-supported tungstic acid (STA): A new, highly efficient and recyclable catalyst for the synthesis of 1H-pyrazolo1,2-bphthalazine-5,10-dione carbonitriles and carboxylates under neat conditions

摘要

1H-Pyrazolo1,2-6phthalazine-5,10-dione carbonitriles and carboxylates possess a broad range of applications as active compounds in the pharmacological and biological fields. We developed an efficient and ecofriendly silica gel-supported tungstic acid (STA)-catalyzed one-pot synthesis of 1H-pyrazolo1,2-bphthalazine-5,10-dione carbonitriles and carboxylates by a three-component reaction of an aldehyde, a malononitrile/ethyl cyanoacetate and a phthalhydrazide under solvent-free conditions. The major advantages of the present method are experimental simplicity, use of an inexpensive and ecofriendly reusable catalyst, good yields, and short reaction times. (C) 2014 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.