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