Silver-catalyzed cascade reactions of 3-cyanochromone with 1,1-enediamines: synthesis of highly functionalized 2-(pyridin-3-yl)-chromeno[2,3-d]pyrimidines

A novel protocol for the construction of highly functionalized 2-(pyridin-3-yl)-chromeno[2,3-d]pyrimidines (PCPMDs) from 3-cyanochromone with 1,1-enediaminesviaan unprecedented cascade reaction has been developed by simply refluxing a mixture of 3-cyanochromone1and various types of 1,1-enediamines2under the catalysis of silver carbonate. As a result, a series of PCPMDs3were obtained through a novel cascade reaction involving an amazing electrocyclization mechanism of a cyano group with alpha,beta-unsaturated nitriles. This reaction formation of PCPMDs was accompanied by the formation of four bonds and the cleavage of one bond in one step. This protocol can be used for the synthesis of various pyridin-3-yl-substituted complex pyrimidine derivatives, and it is suitable for combinatorial and parallel syntheses of PCPMD drugs or natural-like products.