N-Alkylations of Two Indole Derivatives

The N-alkylations of methyl 3-indoleglyoxylate and indole-3-acetonitrile were carried out using alkyl halides or sulfonates as electrophiles in the presence of bases and six new N-alkylation products of indole derivatives were prepared. The influences of the structures of indole derivatives and electrophiles, the solvents and bases on the alkylations have been studied. The N-alkylation of methyl 3-indoleglyoxylate with a strong electron-withdrawing group could be conducted using weak base Cs2CO3 in mild reaction condition and in 93% yields while a strong base such as NaH must be used when indole-3-acetonitrile with a weak electron-withdrawing group was used as reactant in the N-alkylation.