A facile synthesis of novel unsymmetrical bis-spiro[indole-pyrazolinyl-thiazolidine]-2,4 '-diones

An elegant synthesis of some novel unsymmetrical bis-indol-2,3-diones (4a-d) has been achieved via 1-(6- bromohexyl)-1H-indol-2,3-diones (3a,b). These compounds have been further used for the synthesis of novel bis-spiroindoles (7a-d) via hitherto unknown bis Schiff's bases (6a-d).