Investigation On Silver-catalyzed Cyclization/Sulfonylation Of Enynes

The cyclic compounds are significant frameworks of many biologically active molecules and natural pharmaceutical molecules.It is an extremely useful tool for constructing these cyclic compounds by cycloisomerization of enynes.It features in atom-economy,step-efficiency and readily available starting materials.Most notably,transition metal catalysis enables these polyunsaturated substrates to link with various special function groups under mild conditions,which afford diverse functional molecules.On the other hand,the sulfonyl group has been the hotpot in the field of organic synthesis owing to its distinctive structure and electronic features,which lead them to a wide-range application in organic synthesis and medicinal chemistry.Therefore,the development of synthetic methods for introducing sulfonyl group by different sulfonyl regents is in great progress.In this regard,the topic of this research is to develop efficient methods for the construction of valuable sulfonylated heterocycles by easily available 1,6-enynes and suitable sulfonyl reagents.The details are listed as follows:In Chapter two,we have developed a novel strategy for the synthesis of sulfonylated lactones via Ag-catalyzed radical addition/cyclization reaction of 1,6-enynes and sodium sulfinates.The reaction presents high stereoselectivity under mild conditions with C4 prochiral center construction in one step.The ESR experiments and relevant mechanistic studies indicated that a radical pathway should be involved in this transformation.In Chapter three,we empoly the radical strategy to synthesize sulfonylated benzofurans via Ag-catalyzed oxdative cyclization of phenyl-linked 1,6-enyens with sodium sulfinates in one-step manner,which distinguished from the traditional transition metal-catalyzed methods.It features in atom-and step-economy without substrate prefunctionalization.The reaction conditions are mild with wide-range substrate scope.