X-Ray Crystal Structure Analysis of Novel 6-Amino-3-Phenyl-4-(Pyridin-4-yl)-2,4-Dihydropyrano[2,3- c ]pyrazole-5-Carboni
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TRUCTURE OF ORGANIC COMPOUNDS
X-Ray Crystal Structure Analysis of Novel 6-Amino-3-Phenyl-4(Pyridin-4-yl)-2,4-Dihydropyrano[2,3-c]pyrazole-5-Carbonitrile S. Sharmaa, G. Brahmacharib, and V. K. Guptac,* a
b Laboratory
Department of Physics, GDC (Boys) Kathua, J&K (UT)-184101, India of Natural Products and Organic Synthesis, Department of Chemistry, Visva-Bharati (a Central University), Santiniketan, West Bengal, 731235 India c Department of Physics, University of Jammu, Jammu Tawi, 180006 India *e-mail: [email protected] Received February 19, 2020; revised April 11, 2020; accepted April 14, 2020
Abstract—The communication deals with the eco-friendly synthesis and X-ray crystal structure of an organic carbonitrile, namely 6-amino-3-phenyl-4-(pyridin-4-yl)-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile. The title compound was synthesized in 89% yield by following a simple, straightforward and highly efficient multicomponent one-pot protocol under the excellent catalytic influence of non-toxic trisodium citrate dihydrate under ambient conditions. X-ray diffraction studies reveal the packing of molecules in the crystal, which is strongly influenced by both intra and intermolecular hydrogen interactions. In addition, aromatic π–π interactions stabilize the molecular chains propagating along [001]. DOI: 10.1134/S1063774520070184
INTRODUCTION Pyrano[2,3-c]pyrazole moiety is considered as a pharmacologically promising substructure with numerous biological effects, such as anticancer [1], antimicrobial [2, 3], anti-inflammatory [4], antiangiogenesis [5], and molluscicidal activity [6]. Recently, a series of synthetic heterocycles bearing a pyrano[2,3-c]pyrazole moiety in their molecular architecture has been evaluated to possess potent antimicrobial [7], anti-inflammatory [8], Chk1 inhibitor activity [9], anticancer [10], and analgesic activity [11]. Here we report chemically sustainable facile synthesis and detailed X-ray crystallographic studies of a new such compound, 6-amino-3-phenyl-4-(pyridin-4yl)-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile. EXPERIMENTAL Synthesis The novel pyrano[2,3-c]pyrazole derivative (5) was first synthesized based on the commercially available trisodium citrate dihydrate as an inexpensive and ecofriendly catalyst via one-pot tandem Knoevenagel cyclocondensation of malononitrile (3), pyridine 4carboxy-aldehyde (4) and in situ generated 3-substituted-1H-pyrazol-5(4H)-ones (2) in aqueous ethanol at room temperature (Fig. 1). 3-Propyl-1H-pyrazol5(4H)-one (2) was first obtained in situ from the reaction of hydrazine hydrate (0.050 g, 1 mmol) with ethyl 3-oxohexanoate (1; 0.158 g, 1 mmol) with vigorous
stirring at room temperature for 10 min in an ovendried screw cap test tube charged with a magnetic stir bar. Malononitrile (1; 0.072 g, 1.1 mmol), pyridine 4carboxyaldehyde (4; 0.107 g; 1 mmol), trisodium citrate dihydrate (10 mol %; 0.03 g), and ethanolwater (1 : 1 vol/vol; 4 mL) were sequentially added to the reaction tube containing in situ generated 3-substituted-1H-pyrazol-5(4H)-one
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