Free-radical Tandem Cyclization Reaction Of ?,?-Unsaturated Aryl Aldehyde(ketone)

Compared with traditional synthesis methods,radical tandem reaction has the advantages of high atom utilization,high reactivity,and good selectivity.The development of radical tandem reactions for the construction of complex polycyclic compounds is of great significance in organic synthesis.Compounds such as ketones,esters and amides containing?,?-unsaturated structural units are prone to radical addition/cyclization reactions and are the most commonly used substrates for tandem reactions.This dissertation focuses on the free radical tandem cyclization reaction involving?,?-unsaturated aryl aldehydes(ketones),and the main contents include the following three parts:(1)An effective strategy for the preparation of 10,10-disubsituedphenanthren-9(10H)-ones via a photo-driven radical addition/cyclization of biaryl vinyl ketones with CF₃SO₂Na has been developed.The reactions can proceed smoothly in air under 380–385 nm LED irradiation without any external photocatalyst.A functionalized difluoromethylated unit was used in this transformation,such as potassium 2,2-difluoro-2-arylacetate,ethyl bromodifluoroacetate and bromodifluoroacetamide.The desired products can be obtained in good yields.(2)A new method for the preparation of 10,10-disubsituedphenanthren-9(10H)-ones was developed by the decarboxylative addition/cyclization reaction between biaryl vinyl ketones and benzoyl peroxide through microwave radiation under transition-metal-free conditions.The cyclization reaction can be efficiently completed within 30 minutes under microwave irradiation using water as the solvent.The advantages of this method are characterized by simple reaction conditions,high product yield,and good functional group tolerance.(3)Using acenaphthylene quinone as photocatalyst,the intramolecular cyclization of biaryl-2-carbaldehyde was achieved under blue light irradiation,and a series of biologically active fluorenone and its derivatives were synthesized.The reaction needs no additional additives and it has the advantages of simple reaction conditions,high reaction yield and good tolerance of functional groups.