A new synthesis of imidazo[1,2-a]pyridine and imidazo[2,1-a]isoquinoline derivatives

A new synthesis of imidazo1,2-a]pyridine and imidazo2,1-a]isoquinoline derivatives 4 and 8 , respectively by 1,5-dipolar cyclization reactions of stabilized pyridinium N-ylides 3a-e or isoquinolinium N-ylide 7 is described. The starting N-ylides 3a-e and 7 are prepared by the reaction of the corresponding pyridinium salts 1a-e or isoquinolinium salts 6 with N-bis(methylthio)methylene-p-toluenesulfonamide (2) .