Study On Synthesis Of Nitrogen Containing Heterocyclic Derivatives By Iodine-promoted Tandem Reaction

In recent years,oxidation coupling reaction has been rapidly developed and already become a common method to construct carbon-heteroatom bonds.Compared to conventional coupling reaction,the oxidation coupling reaction not only reduces the complicated pre-functionalization of the substrates,shortens the reaction route,and improves the reaction efficiency,but also increases the source of raw materials.Moreover,the oxidative coupling reaction greatly improves the practicality of the reaction and reduces the production cost.Elemental iodine and hypervalent iodine(III)compounds as common oxidants are inexpensive,lower toxic and structural stable which possess the advantages of easy operation,mild reaction conditions,good regio-and stereoselectivity and act important roles in the synthesis of drugs,natural products,agricultural chemicals and new materials.In this article,our research focus on the applications of elemental iodine or hypervalent iodine(III)reagent to the initiate oxidative coupling for the synthesis of functional nitrogen-heterocyclic compound.The main contents are as follows:In chapter 1,the applications of hypervalent iodine(III)reagent in the synthesis of nitrogen heterocyclic compounds and the research progress in the direct activation of aryl C-H bond by iodine to form C-S bond are reviewed.According to the reaction mechanisms and types of boning,advances in the hypervalent iodine reagent(?)-triggered intramolecular or intermolecular cyclization reaction of synthetic nitrogen heterocyclic are summarized in detail,and the reaction mechanism is discribed emphatically.Secondly,the advantages in the construction of C-S by iodine are demonstrated through direct oxidation of aromatic C-H bond and the formation of C-S bond?In chapter 2,sulfonylation of pyridine/quinoline N-oxides induced by iodine is developted.The sulfonyl anions attack C2 of pyridine/quinoline N-oxides and the iodic acid combines with the N-oxide groups which are the key steps to synthesize N-heteroaromatic sulfones by a one-pot method of pyridine/quinoline N-oxides with sulfonyl hydrazine.Compared with literature methods,great advantages of this strategy include a wide range of reaction substrates,an efficient time-saving one-pot procedure,mild and metal-free reaction conditions and free pre-functionalization.In chapter 3,the novel synthesis method of dihalo-2,3-dihydropyrroles is efficiently studied.This method provides an access to the target molecules via reaction of homopropargyl sulfonamides with hypervalent iodine(?)and copper halides in one pot under mild conditions.The synthesized target molecules are important intermediates to produce pentabromo-and pentachloropseudilin and have important practical value.In chapter 4,a new PhI(OAc)2-mediated 1,2-aminohalogenation of prop-2-yn-1-yl carbamates and various halogen sources is presented with excellent selectivity and high step-economy.The study shows that the triple bond activated by PhI(OAc)2 to form halonium ion and then occur lactamization,when copper haildes were used as the halogen source.Meanwhile,when non-metallic halogensources were used,the reaction can be through the aminyl radicals to occur lactamization.