Pd(?)-catalyzed Intramolecular Cope-Type Hydroamination Reaction

Nitronone is a kind of highly active compound,widely used in the synthesis of heterocyclic and natural products.It also has therapeutic and biorthogonal labeling applications.Synthesis methods include oxidation of amine and hydroxylamine,condensation,oxime alkylation,rearrangement and so on.These traditional methods are lags far behind the modern requirement of atom-economy,stereocontrol,et.al.It is of significance and practical value to develop practical methods for the synthesis of cyclic nitrones.Herein,we developed a Pd(?)-catalyzed intramolecular Cope-type hydroamination reaction.The scope and limitations of the cope-type hydroamination reaction catalyzed by Pd(?)have been preliminarily explored.Among several types of oxime compounds,including carbon and nitrogen tethered vinyl oximes,cyclic nitrone compounds of 5 and 6 membered can be formed effectively,and the yield is moderate to good.Through the comparative study of these different types of substrates,a reactivity trend can be determined,that is,the less Lewis basic oximes more easily cyclize possibly due to more facile migratory insertion step.Moreover,this reaction is insensitive to air and moisture and easy to perform.