Microwave-assisted synthesis of indole- and azaindole-derivatives in water via cycloisomerization of 2-alkynylanilines and alkynylpyridinamines promoted by amines or catalytic amounts of neutral or basic salts

An efficient methodology is described and exploited for the preparation of differently substituted indoles and azaindoles via microwave-assisted cycloisomerization in water of 2-alkynylanilines and alkynylpyridinamines, which is promoted by catalytic amounts of neutral or basic salts or by stoichiometric weak organic bases. Good to high yields in the cyclization can be achieved for a variety of 2-amino(hetero)aryl alkynes. Reactions are run without any added metal catalyst. A comparison with the cycloisomerization conducted under conventional heating is also described.

Graphical abstractAn efficient methodology is described for the preparation of differently substituted 1H-indoles and 1H-azaindoles via microwave-assisted cycloisomerization in water of 2-alkynylanilines and alkynylpyridinamines, promoted by catalytic amounts of neutral or basic salts or by weak organic bases.Figure optionsDownload full-size imageDownload as PowerPoint slide