One-pot synthesis of 1, 2-disubstituted 4-, 5-, 6-, and 7-azaindoles from amino-o-halopyridines via n-arylation/sonogashira/cyclization reaction

A direct synthesis of several 1, 2-disubstituted 4-, 5-, 6-, and 7-azaindoles from available amino-o-halopyridines is described. This procedure involves a palladium-catalyzed N-arylation followed by a Sonogashira reaction and subsequent cyclization in a one-pot manner, exhibiting a wide scope and compatibility with electron-withdrawing and electron-donating groups. The strategy represents an advancement in azaindole chemistry with a straightforward approach toward 1, 2-disubstituted azaindoles, while avoiding complex N-arylations of hindered 2-substituted azaindoles and difficult purification steps of intermediates.