Study On Phosphine-Catalyzed Annulation Reaction Of Morita-Baylis-Hillman (MBH) Carbonates

Nitrogen-containing heterocyclic compounds are widely used in the medicine, spices, pesticides and dye industry. Their high biological activity and low toxicity have attracted much attention in the area of pesticide and medicine. Therefore, developing a kind of economic and highly efficient methodology for synthesis of nitrogen-containing heterocyclic compounds, is highly desirable.Nucleophilic phosphine-catalyzed annulation reactions have been developed as one of the most powerful tools for synthesis of heterocyclic compounds, and various annulation reactions have been achieved. Phosphonium enolate zwitterions, that were formed through nucleophilic attack of the phosphine catalysts at Morita-Baylis-Hillman (MBH) carbonates, often work as a one or three-membered synthon to react with various electrophilic coupling partners, leading to various annulation. In this paper, phosphine-catalyzed [3+3] annulation of Morita-Baylis-Hillman carbonates with C,N-cyclic azomethine imines and its asymmetric variant are described. Phosphine-catalyzed [3+2] cycloaddition of Morita-Baylis-Hillman carbonates with sulfamate-derived cyclic imines has also been developed, affording novel heterocyclic products containing pyridazine and dihydropyrrole moieties. It can also provide methodology basis for related heterocyclic compounds. The content is as follows:1.(R)-SITCP catalyzed [3+3] annulation of Morita-Baylis-Hillman carbon&es with C,N-cyclic azomethine imines and its asymmetric variant have been achieved. The reaction worked smoothly under mild conditions to afford a wide range of heterocyclic compounds combining pyridazino and isoquinoline moieties in moderate to excellent yields with good to excellent diastereoselectivities and extremely excellent enantioselectivities. The cycloadducts could be further transformed to very useful heterocyclic molecules through reduction or coupling reaction.2. Phosphine-catalyzed [3+2] cycloaddition of MBH carbonates with sulfamate-derived cyclic imines has been developed, affording dihydropyrroles derivatives in moderate to good yields with excellent regioselectivities and diastereoselectivities. 3. The thermal [3+2] cycloaddition reactions of two classes of aromatic azomethine imines with allenoates have also been investigated when exploring the cycloaddition of the aromatic azomethine imines. The reactions are operationally simple and proceed smoothly under mild reaction conditions to provide a variety of dinitrogen-fused heterocycles in moderate to excellent yields. These nitrogen-heterocyclic products are different from the products formed by phosphine-catalyzed annulations of azomethine imines with allenoates, and could be useful for the investigation of new compounds on bioactivities.