Diverse reactivity of isatin-based ,′-cyclic azomethine imine dipoles with arynes: synthesis of 1′-methyl-2′-oxospiro [indene-1,3′-indolines] and 3-aryl-3-pyrazol-2-oxindoles

• Published in: New journal of chemistry 2020-07, Vol.44 (27), p.11593-1161
• Main Authors: Meerakrishna, Ramakrishnan Suseela, Smile, Suresh Snoxma, Athira, Mohanakumaran, Choutipalli, Venkata Surya Kumar, Shanmugam, Ponnusamy
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/d0nj01684e

The reaction of aryne with isatin-based N , N ′-cyclic azomethine imine 1,3-dipole afforded 3,3-disubstituted oxindole bearing a pyrrolidine ring and a quaternary stereocenter in very good yield. In contrast, methyl substitution on the pyrrolidine ring of 1,3-dipole directed [3+2] cycloaddition with aryne gave a mixture of column separable diastereomers of the cycloadduct with moderate diastereoselectivity in excellent yield. A plausible reaction mechanism is provided. The experimental results were supported by DFT calculations. Furthermore, the synthesized 3,3-disubstituted oxindole was synthetically transformed to a 1,3-diyne derivative. Reaction of aryne with isatin based N , N ′-cyclic AMI 1,3-dipole afforded 3,3-disubstituted oxindole while methyl substitution on the pyrrolidine ring of 1,3-dipole directed [3+2] cycloaddition products.