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.

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.