Studies On Domino Cyclization Reaction Of ?-carbonyl Ketene Dithioacetals

With current the increasing shortage of natural resources and environmentworsening, implementing sustainable development has become essential. Hence, it isserious challenges for organic chemists to develop efficient synthesis methods whicheliminate or reduce emissions from the source. Domino reaction rapidly becomes oneof hot research areas in organic chemistry because of its advantage, such as simple,high efficiency, high atomic economy, without isolation of intermediate products, lowenvironmental pollution and so on.In this thesis, based on the development of a highly efficient, simple dominoreaction, together with a core of achieving simple and efficient cyclization reaction,we mainly study the bicyclic reaction of ?-oxo ketene dithioacetals containing double1,5-dielectrophilic systems and various dipoles as well as the radical-directed cascadeintermolecular coupling and intramolecular cyclization reaction of ?-oxo ketenedithioacetals with diphenylmethane derivatives. This thesis mainly includes thefollowing three aspects:A domino bicyclization reaction of ?-alkenoyl ketene dithioacetals of1,5-dielectrophilic systems with methyl isocyanide derivatives has been developedand a series of hydrogenated indolones were obtained in the presence of NaOH. Thissingle step process involves a sequent [5+1] cycloaddition/intramolecular [3+2]cyclization where up to three chemical bonds and two rings are createdsimultaneously in one-pot. This protocol is associated with concise synthesis route,mild reaction conditions, high atom economy and regional selectivity.A domino bicyclization reaction of the ?-alkenoyl ketene dithioacetals with1,5-dielectrophilic systems with diazo compounds has been developed in the presenceof DBU. The reaction provides a highly efficient strategy for the direct synthesis of4H-pyrrolo[1,2-b]pyrazol derivatives through the tandem1,3-dipolarcycloaddition/intramolecular aza-Michael addition/oxidative aromatization reaction ofthe readily available acyclic precursors in single step.A radical-directed ?-functionalization of ?-oxo ketene dithioacetals withdiphenylmethane derivatives has been carried out under metal-free conditions in thepresence of DDQ, namely the intermolecular cross-dehydrogenative coupling (CDC)reaction of Csp2–H bonds of alkenes with alkyl Csp3–H bonds not adjacent toheteroatoms. On this basis of this reaction, a new, general and highly efficient strategy for the direct synthesis of polysubstituted indene compounds has been developed via asequent intermolecular C(sp2)–C(sp3) bonds and intramolecular C(sp2)–C(sp2) bondscross-dehydrogenative coupling reactions in single step.