Letters in Organic Chemistry   Rahele Doosti 1 , Mohammad Bakherad 1,* , Mahdi Mirzaee 1,* and Khosrow Jadidi 2 1 School of Chemistry, Shahrood University of Technology, Shahrood 3619995161, Iran; 2 Department of Chemistry, Shahid Beheshti University, Tehran 1983963113, Iran A R T I C L E H I S T O R Y Received: November 23, 2016 Revised: February 25, 2017 Accepted: April 06, 2017 DOI: 10.2174/1570178614666170505113009 Abstract: Background: The design of biologically-active compounds is a challenging viewpoint in medicinal chemistry, and pyrazoles play a crucial role as biologically-active molecules. Methods: Up to now, a few examples have been reported for the synthesis of pyrazoles catalyzed by heterogeneous catalysts. In this work, a new boehmite silylpropyl amine sulfamic (m-SABNPs) was applied as a catalyst for one-pot synthesis of pyrazole derivatives. Results: It was found that this heterogeneous sulfamic acid is a highly efficient catalyst for the synthe- ses of 5-amino-1,3-aryl-1H-pyrazole-4-carbonitriles and pyrazolopyranopyrimidines in good to excel- lent yields and can be recovered by a simple filtration of the reaction solution and reused for five con- secutive runs without significant loss of catalytic activity. Moreover, its structure was characterized by FT-IR spectroscopy, TGA, XRD, TEM and SEM techniques. Conclusion: An efficient, and convenient method was proposed for the synthesis of pyrazole deriva- tives catalyzed by heterogeneous sulfamic acid in high-to-excellent yields. This method offers several advantages like milder reaction condition, shorter reaction time, cleaner reaction, and reusability of the catalyst. Keywords: Boehmite nanoparticle, reusable catalyst, sulfamic acid, pyrazoles. 1. INTRODUCTION Sulfamic acid (NH 2 SO 3 H, SA) is an odorless, non-volatile, non-hygroscopic, incorrodible, crystalline solid acid with outstanding catalytic properties in the heterocyclic synthesis. Moreover, the catalytic activity of solid acids could be effi- ciently increased by their immobilization onto a nanomate- rial solid support with a high surface area. When the size of such a support decreases to a nanometer scale, surface area considerably increases, and the support can be evenly dis- persed in solution to form a homogenous emulsion [1]. Boehmite is aluminum oxide hydroxide (γ-AlOOH), com- prising additional hydroxyl groups on its surface. Among the various techniques utilized for the production of BNPs, the hydrothermal-assisted sol-gel hydrolysis of aluminum alkox- ides, which is a one-pot procedure at low temperature, was used in this work. The most encouraging property of this method is the development of a crystalline single-phase product with no organic residues [2, 3]. Mirzaee et al. have recently reported the epoxidation of different olefins using *Address correspondence to these author at the School of Chemistry, Shah- rood University of Technology, Shahrood 3619995161, Iran; Tel: +982332395441; E-mails: m.bakherad@yahoo.com; mmirzaee@shahroodut.ac.ir oxosulfate vanadium(IV) and hexacarbonyl molybdenum complexes anchored onto the amine and/or Schiff base func- tionalized BNPs [4-6]. Pyrazoles and their derivatives are extensively used as pharmaceuticals and agrochemicals, the earliest example, antipyrine, dating from 1884 [7, 8]. Literature survey has revealed that a number of methods have been reported for the synthesis of pyrazole nucleus [9-11]. On the other hand, only a few examples of the synthesis of pyrazoles in the presence of heterogeneous catalysts such as CsF-Al 2 O 3 [12], silica chloride [13], and CuO/ZrO 2 [14] have been mentioned in the literature. In continuation of our studies on the applica- tion of BNPs in organic synthesis [15, 16], herein we wish to report a simple, rapid, and green synthetic method for the syntheses of 5-amino-1,3-aryl-1H-pyrazole-4-carbonitriles, di- hydropyrano[2,3-c]pyrazoles, and pyrazolopyranopyrimidines, catalyzed by BNPs -sulfamic acid (m-SABNPs) (Scheme 1). 2. RESULTS AND DISCUSSION 2.1. Catalyst Preparation m-SABNPs was prepared as shown in Scheme 2. Ini- tially, BNPs were prepared according to a reported procedure [2]. Then it was refluxed with trimethoxysilylpropyl amine 1875-6255/17 $58.00+.00 © 2017 Bentham Science Publishers benthamscience.ae 450 RESEARCH ARTICLE Boehmite Silylpropyl Amine Sulfamic Acid as an Efficient and Recyclable Catalyst for the Synthesis of some Pyrazole Derivatives Letters in Organic Chemistry, 2017, 14, 450-46 Send Orders for Reprints to reprints@