1: 1-(2-methylphenyl)pyrrole With n-butyllithium; N,N,N',N'',N''-pentamethyldiethylenetriamine in tetrahydrofuran T=-75°C; 1 h; 2: carbon dioxide in tetrahydrofuran T=-75°C;

1: 1-(2-methylphenyl)pyrrole With n-butyllithium; N,N,N',N,-tetramethylethylenediamine in diethyl ether T=0°C; 1 h; 2: carbon dioxide in diethyl ether T=0°C;