Silver-Catalyzed Multicomponent Reaction Involving Carbon Dioxide For The Synthesis Of Carbamates

Organic carbamates constitute an important class of biologically active compounds.They are the basic skeleton of many drug molecules and versatile synthetic intermediates,which have wide-spread applications in pharmaceuticals,agrochemicals and organic synthesis.The conventional methods for the synthesis of organic carbamates mainly rely on the use of highly toxic phosgene and its derivatives as the raw material,which can easily have a detrimental influence on the environment and cause safety concerns.Carbon dioxide is not only the main greenhouse gas,but also one of the most abundant,safe,and renewable C1 resource.Thus it is of great significance to develop new methods for the synthesis of carbamates using carbon dioxide instead of phosgene.In this paper,two new methods for the synthesis of carbamates from carbon dioxide have been successfully developed.(1)A silver-catalyzed three-component coupling reaction of carbon dioxide,amine and allyl ether was developed.The reaction employs AgOAc as the catalyst and TBD as the base,providing an effective route for the synthesis of O-aryl carbamates.Mild reaction conditions,high chemo-and regio-selectivity,good functional group compatibility and wide substrate scope are the features of the method.(2)A silver-catalyzed three-component reaction of carbon dioxide,amine and ?-diazoesters was developed,providing an efficient and practical synthetic methodology of a wide range of ?-carbamoyloxy esters,which are difficult to prepare by existing methods.This reaction only requires AgOAc as the catalyst and have many advantages such as the use of readily available starting materials,good atom economy and high functional group tolerance.