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Oxidative Cleavage Of C-N Bonds And Alkenes Synthesis

Posted on:2015-02-18Degree:MasterType:Thesis
Country:ChinaCandidate:Y G ZhangFull Text:PDF
GTID:2251330398483104Subject:Organic Chemistry
Abstract/Summary:PDF Full Text Request
Carbon-nitrogen bonds are common existed in a large amount of organic molecules. Although enormous progress has been accomplished for the cleavage of carbon-nitrogen bonds, the olefination of carbon-nitrogen bonds under specific condition is rare. The arylation of alkenens under metal-catalyzed coupling reaction and imines olefination are important methods for the construction of carbon-carbon double bonds. We have discovered that aroyl hydrazides, a class of compounds containing carbon-nitrogen bonds, which can lose the NHNH2group, extrude of carbon monoxide and form a active aryl palladium intermediates in the presence of a palladium catalyst, could couple with alkenes; N-aryl secondary amines therefore can be oxidized to imines by metal-free oxidants and the imines intermediates can be further olefinated by nucleophiles in one pot.This paper was divided into four parts.Part1:Give a brief overview of current research on converting of C-N bonds to C=C bonds, oxidizing secondary amines to imines and olefinating of imines.Part2:We report a Mizoroki-Heck coupling reactions between aroyl hydrazides and alkenes under palladium-catalyzed reaction. In the presence of acid, we found the aroyl hydrazides could arylate terminal alkenes with excellent regio-and E-selectivity under the catalysis of palladium chloride/cupous iodide in dimethyl sulfoxide/acetonitrile open to air at100℃. Control experiments indicated that the air and DMSO serve as the oxidant, and PdCl2serves as the major active Pd11catalyst. On the basis of aroyl hydrazides decomposition reaction and the side products assignment by ESI-Mass analysis of the reaction mixture, we envisioned that aroylpalladium and arylpalladium are formed from aroyl hydrazides during the reaction and proposed possible reaction pathways.Part3:We report an oxidative olefination of secondary amines with2-alkyl-azaarenes, acetophenone and malononitrile. In the presence of a stoichiometric amount of2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), certain2-alkylaza-arenes such as2-alkylquinolines,2-methylquinoline,2-methylquinazoline can undergo C-H olefination with secondary amines and give structurally diverse polysubstituted alkenes in excellent yield with excellent E-selectivity. Control experiments and mechanistic studies revealed that the reaction proceeds through secondary amines oxidation and DDQH2-catalyzed Mannich-type addition and the intermidiates elimination.Part4:We report an oxidative olefination of secondary amines with α-(benzothiozol-2-ylsulfonyl) carbonyl compounds. In the presence of a stoichiometric amount of2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), secondary amines was oxidized to imines, which can be further olefinated by α-(benzothiozol-2-ylsulfonyl) carbonyl compounds through imines addition, Smiles rearrangement and decomposition to yield α, β-unsaturated carbonyl compounds with excellent E-selectivity.
Keywords/Search Tags:alkenes, arylation, hydrazides, oxidation, palladium, homogeneouscatalysis, amines
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