Stereo and regioselective synthesis, structural elucidation and antibacterial activity of novel spiropyrrolidine embedded with two units of oxindoles

Abstract

An excellent yield of spiropyrrolidine grafted with two units of oxindole moieties was obtained employing a one-pot three component 1,3-dipolar cycloaddition cascade reaction strategy. In this cascade reaction, the key intermediate 1,3-dipole compound is formed in situ from isatin and l-phenylalanine, which was further reacted with highly functionalized 3-benzylideneindolin-2-one to form structurally complex heterocycles viz. 5-benzyl-2-spiro[2.3′]-3-spiro[3.3′′]-4-chlorophenylpyrrolidine with broad substrate diversity. The formation of a stereoselective spirocycloadduct with four contiguous stereogenic centers, two of which are spirocarbons. The structure of compound 4 was assigned through one-, two-dimensional NMR and mass spectroscopic analyses. The structure of the spiroadduct was undoubtable determined through single crystal analysis. The supramolecular structure aspects of 4 was found to depend on the O…H, N…H, C…O, and H…H interactions. Their percentages are 49.4, 24.4, 1.0 and 11.1%, respectively based on Hirshfeld analysis. The DFT/B3LYP optimized structure is found to agree well with the experimental one. Compound 4 has significant polarity where the calculated dipole moment is 4.2147 Debye. The antibacterial efficacy of the compound 4 showed more sensitive results against Shigella sp. (19.00±0.30 mm) followed by Acinetobacter sp. (17.00±0.15 mm), besides, the compound 4 showed notable antioxidant properties.