Synthesis of new spiro compounds containing a carbamate group

1,3-Dipolar cycloaddition to methyl 4-2-(2-oxo-2,3-dihydro-1H-indol-3-ylidene)-1-oxoethyl]-phenylcarbamate of diazomethane in chloroform-diethyl ether and of 3,4-dimethoxybenzonitrile oxide generated from the corresponding aldehyde oxime by the action of N-chlorobenzenesulfonamide sodium salt (Chloramine B) in boiling ethanol gave, respectively, methyl 4-(2-oxo-1′,5′-dihydro-1H-spiroindole-3,4′-pyrazol]-3′-ylcarbonyl)phenylcarbamate and methyl 4-3′-(3,4-dimethoxyphenyl)-2-oxo-1H,4′H-spiroindole-3,5′-isoxazol]-4′-ylcarbonyl]phenylcarbamate. The condensation of methyl 4-2-(2-oxo-2,3-dihydro-1H-indol-3-ylidene)-1-oxoethyl]phenylcarbamate with hydrazine hydrate in ethanol afforded methyl 4-(2-oxo-1,2,2′,4′-tetrahydrospiroindole-3,3′-pyrazol]-5′-yl)phenylcarbamate.