One pot synthesis of novel 1, 2-dihydro-5-methyl-spiro[4<i>H</i>-3,1-benzoxazine-2,3'[3<i>H</i>]indol]-4,2'-diones

Abstract

2381-2385A facile one pot synthesis of some novel spiro heterocycles such as 5-methyl-spiro [benzoxazine-indol]-4,2'-diones 3a-j is carried out by cyclocondensation of indole-2,3-diones 1a-j with 6-methylanthranilic acid 2 in ethanol under dry condition. The importance of substituent at C-6 position in 2 has been highlighted in such condensation reactions. The molecular modelling has shown that such substitution perfectly aligns the carboxyl group for intramolecular cyclization to take place. The reaction is of great value because of its environmentally benign character as non-toxic chemicals are used and no waste is generated