1: 1-methyl-2,3-indolinedione With sodium amalgam in N,N-dimethyl-formamide T=20°C; 4 h; 2: 2-methyl-1-(toluene-4-sulfonyl)-2,3-dihydro-1H-indole in N,N-dimethyl-formamide T=110°C; 18 h;