Studies On Palladium-catalyzed Aza-Wacker Cyclization

This dissertation is mainly focused on the palladium(II)-catalyzed aza-Wacker cyclization,aiming to rationalize the cyclization pathway of different amides(such as N-tosyl carboxamide and N-methoxy carboxamide)to construct varies ring systems,which will be facilitate the future design of hetereocycles.Part One: A series of five and six-membered nitrogen heterocycle rings were constructed in high yields by aza-Wacker cyclization of amides bearing an internal olefin(12 examples).It is of particular interest that construction of the five-membered rings bearing nitrogen-containing quaternary center through this method.Substrates bearing N-tosyl carboxamides N-methoxy carboxamide both delivered the requisite cycled hetereocycles via a highly selective exo-manner,and reactivity of the former was superior to reactivity of the latter.Part Two: This part mainly focused on the aza-Wacker cyclization of amide substrates bearing a terminal alkene(14 examples).For the different length of carbon chain,for the cyclization of N-tosyl carboxamides delivered both exo and endo-type products.We also discovered a rare mode of allylic C-H activation in aza-Wacker cyclization to the construction of the medium ring.In contrast,the C-H activation pathway was not dominated in the aza-Wacker cyclization of N-methoxy carboxamide.Morover,a ?-lactam bearing quaternary carbon center was also obtained via cyclization of N-methoxy carboxamide albeit the low isolated yield.Not only a series of monocyclic rings can be constructed but also spiro ring and fused ring can be constructed via cyclization of N-tosyl carboxamide.The preliminary mechanistic studies support trans-amidopalladation process for the cyclization of N-tosyl carboxamide while N-methoxy carboxamide prefers the cis-amidopalladation pathway.