A series of unexpected semi-saturated fused multicyclic iminosugars were synthesized by one-pot stereoselective three-components reactions of D-ribose tosylate, aniline and cycloketenes at heating condition. The N-aryl enamine derived from iminium-ion is the key intermediate for the reaction. As a result, several novel complex fused iminosugars 3a/4a were obtained through aza hetero Diels-Alder mechanism at 80 oC. This strategy will help to prepare the bioactive iminosugar analogues with structural diversity.

An efficient and simple one-pot synthesis of structurally diverse novel tetrahydroquinolin fused iminosugars was developed through the aza-Diels-Alder(Povarov mechanism) mechanism. The adaptability of this method has been demonstrated by a variety of imines and D/L-ribose tosylates, and both electron-donating and withdrawing substituted imines are employed in reaction well. In addition, this reaction is characterized by simple operation, good yield, and high atom economy. Some synthetic iminosugars showed moderate anti proliferation of HCT116 tumor cells.