Solid acid-catalyzed domino cyclization reaction: regio- and diastereoselective synthesis of pyrido[2,3-d]pyrimidine derivatives bearing three contiguous stereocenters.

An efficient and green domino approach for the synthesis of 5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-4(3H)-one derivatives using a recoverable carbonaceous material as a catalyst has been established. The new domino reaction was conducted by reacting the readily available and inexpensive starting materials 2,6-diaminopyrimidin-4(3H)-one, nitroolefin and aldehyde in water. A total of 24 examples were examined, and showed a broad substrate scope and high yields. The carbonaceous material catalyst can be reused at least 5 times without obvious deactivation. The proposed mechanism has explained the reaction process and the resulting high regio- and diastereoselectivities. The present green strategy shows attractive characteristics such as using water as a green medium, using an inexpensive and recoverable solid acid catalyst, and having a simple work-up/purification, without generating any waste products or using any metal promoters. [ABSTRACT FROM AUTHOR]