Synthetic reactions of 2-(2-amino-3-cyano-4H-[1]benzopyran-4-yl)propane-1,3-dinitrile with reactive methylene compounds

Derivatives of dibenzo [b,d]pyran, [1]benzopyrano[2,3-b]pyridine, [1]benzopyron[3,4-c]pyridine and [1]benzopyrano[4,3,2-de][1,6]naphthyridine are obtained from the reaction of 2-(2-amino-3-cyno-4H-[1]benzopyran-4-yl)propane-1,3-dinitrile with compounds containing a reactive methylene group. Consideration of these reactions suggests that the dicyanomethyl group is released from the 4-position of the starting material, and that it mean reacts at the 2-position of the newly formed iminium ion. The 4-position is now available for Michael addition of a compound containing a reactive methylene group, but the nature of the final product depends on the substituents on the methylene group.