Reductive Amination Of Sulfoxides Induced By Halogen Bond Activation

Hydrogen bond, the important noncovalent interaction, has been widely used in asymmetric synthesis and hydrogen catalysis. Halogen bond is similar to hydrogen bond, but it has advantageous features, such as high directionality, interacting atoms are bigger in size and the strength of bond is stronger. However the use of halogen bond is much less than the use of hydrogen bond in organic synthesis up till now. So exploring how to apply halogen bond in organic synthesis is an important subject.This paper mainly explores the activation of sulfoxide by halogen bond, via Pummerer rearrangement reaction we can get target molecules. We use common reagent NBS as activator of DMSO(dimethylsulfoxide), after adding imine(phthalimi-de, sulfonamide, benzotriazole et al.) to the DMSO which is activated by NBS, we can get acetal products. NBP, NCP and N-bromosaccharin can directly react with DMSO get acetals. Firstly, the bromine of NBS and the oxygen of DMSO form the halogen bond. Upon heating, the bromine atom transfer from nitrogen to oxygen, followed by dehypobromous acid, then the sulfonium is formed. Finally, imine attacks the sulfonium to give the products. When imine is added to the dibenzylsulfoxide which is activated by NBS, Interrupted Pummerer rearrangement reaction may occur with the formation of N-S bond. NBP can directly react with dibenzylsulfoxide to construct the N-S bond. The efficiency of NBS to active the DMSO is medium, the scope of the nucleophilic reagents is limited, but this strategy still has practical and theoretical meaning:we extend the road of Pummerer rearrangement reaction, develop a new method to use NBS and enrich halogen bond application.