One-pot green synthesis of biologically relevant novel spiro[indolin-2-one-3,4′-pyrano[2,3-c]pyrazoles] and studies on their spectral and X-ray crystallographic behaviors

Abstract

Syntheses via green route and single-crystal X-ray structural investigations have been carried out for three spiro[indolin-2-one-3,4'-pyrano[2,3-c]pyrazole] derivatives, 6'-amino-2-oxo-3'-propyl-2'H-spiro[indoline-3,4'-pyrano[2,3-c]pyrazole]-5'-carbonitrile dimethyl sulfoxide monosolvate (5a), 6'-amino-5-fluoro-2-oxo-3'-propyl-2'H-spiro[indoline-3,4'-pyrano[2,3-c]pyrazole]-5'-carbonitrile dimethyl sulfoxide monosolvate (5b) and methyl 6'-amino-5-cyano-1-methyl-2-oxo-3'-propyl-2'H-spiro[indoline-3,4'-pyrano[2,3-c]pyrazole]-3'-carboxylate 0.25 hydrate (5c), respectively. Compounds (5a) and (5b) crystallize in the triclinic space group P\bar 1, whereas compound (5c) crystallizes in the monoclinic space group C2/c. In molecules (5a) and (5b) all the rings are practically flat, while in (5c), the heterocyclic pyran ring adopts a flattened-boat conformation. In (5a) and (5b) the cyanide group is oriented in a (-ap) conformation, while the amino group is oriented in a (+ap) conformation with a pyran ring, but in (5c) both the cyanide and amino groups are oriented in a (-ap) conformation with the pyran ring. In the crystal structure of (5a) and (5b), the molecules are linked by an elaborate system of N-H...O and N-H...N hydrogen bonds to generate a zigzag-like construct. In (5c) molecules are linked by N-H...O hydrogen bonds, thereby generating extended chains. The present communication focuses on the detailed and comparative information about spectral behaviors, single-crystal X-ray crystallographic properties and solid-state supramolecular architectures of these synthesized compounds of potential biological interests.

Synthesis and Characterization of New Pyrano[2,3-c]pyrazole Derivatives as 3-Hydroxyflavone Analogues

“…It is notable that the C(6)-O(7) bond length [1.4135(12) Å] is longer than that in the O(7)–C(7a) [1.3387(12) Å]. The N(1)–N(2) and N(2)–C(3) bond lengths are 1.3839(12) and 1.3458(14) Å, respectively, and agree with the known bond lengths of pyrazole compounds [ 63 , 64 , 65 , 66 ]. The sum of the angles between the covalent bonds around the N(2) atom is 360°, which indicates that a trigonal planar geometry exists at the sp 2 -hybridized nitrogen atom.…”

Advances in the Synthesis of Benzo‐Fused Spiro Nitrogen Heterocycles: New Approaches and Modification of Old Strategies

“…The crystal structure reveals the presence of a DMSO solvent in compounds 36 (R 1 = H, R 2 = H, F, R 3 = C 3 H 7 ) and a quarter of a crystal water is present in compound 36 (R 1 = Me, R 2 = H, R 3 = CO 2 Et; Scheme 11). [128] The approach to the synthesis of spiro heterocycles using the three-component reaction of isatins, 4hydroxycoumarin and phthalyl hydrazide or derivatives of malonic acid (or pyrazoles) in the presence of various catalysts or without it is also quite productive. [132 -134] The reaction direction of isatin 22, 4-hydroxycoumarin 39 and aminopyrazoles 40 under microwave heating conditions depends on the reaction medium, and this circumstance can be advantageously used to obtain two different types of fused spirooxindoles.…”

“…The crystal structure reveals the presence of a DMSO solvent in compounds 36 (R 1 =H, R 2 =H, F, R 3 =C 3 H 7 ) and a quarter of a crystal water is present in compound 36 (R 1 =Me, R 2 =H, R 3 =CO 2 Et; Scheme 11). [128] …”

“…The approaches through the use of multicomponent condensation reactions of isatins, pyrazoles and CH activated molecules with different acidity of the medium are effective in obtaining spirocycles to which pyrazole fragments are annulated [127–131] . The 1,2‐dihydro‐spiro[indole‐3,4′‐pyrano[2,3‐ c ]pyrazoles] 36 were synthesized based on a commercially available trisodium citrate dihydrate as an inexpensive and eco‐friendly catalyst for the first‐time through one‐pot tandem Knoevenagel cyclocondensation of substituted isatins 22 , malononitrile and in situ generated 3‐substituted‐1 H ‐pyrazol‐5(4 H )‐ones 37 or 38 in aqueous ethanol at room temperature.…”

Recent applications of isatin in the synthesis of organic compounds

“…5-fluoroindole 57 in the presence of sulfamic acid as an efficient organocatalyst (Scheme 20). 51 Crystal structure of the product was determined by X-ray structure analysis. In other studies, the reactions of various isatin derivatives 1 and indoles 57 were also investigated in the presence of nano SiO2 52 and Fe3O4@SiO2@SO3H 53 as catalysts.…”