Radical[4+2]Cycloaddition Of Sulfamoyl Azides With Olefins

The Diels-Alder reaction is a powerful method for the synthesis of six-membered rings and plays an important role in the synthesis of many natural and biologically active molecules.For the Diels-Alder reaction,there is a very interesting diene substrate,i.e.,o-methylene benzene,which is 1,3-cyclohexadiene having two ring outer bonds outside the ring.It cannot exist independently,is generated in situ by the precursor in the reaction and then participates in Diels-Alder reaction.Organic azide is an relative stable compound w ith high energy,which can form high reactive nitrene intermediate participating in various reactions.Nitrogen is the only by-product which is environmentally friendly.In combination with our investigation of the use of azido compounds in organic synthesis,we have developed a novel[4+2]cycloaddition reaction.The reaction can proceed under mild reaction conditions with good functional group tolerance.The substrates containing heteroatoms with high coordination ability are compatible.The preliminary mechanism studies show that the reaction processes with a step-by-step radical cycloaddition which is different with the synergistic Diels-Alder reaction.So,the method we developed will be a complement to the classical[4+2]Diels-Alder reaction.