A facile method for the title transformation is described. The reaction of 2,2,6,6-tetramethyl-4-methoxypiperidine oxoammonium chloride (1b) and ketones bearing a-methylene group in acetonitrile proceeded smoothly to ...A facile method for the title transformation is described. The reaction of 2,2,6,6-tetramethyl-4-methoxypiperidine oxoammonium chloride (1b) and ketones bearing a-methylene group in acetonitrile proceeded smoothly to give the a-oxyfunctionalized coupling products (6a-h). These coupling products decomposed upon heating in acidic medium to produce a-diketones (7a-h) in good to excellent yields.展开更多
As one of the most common structural motifs in natural products,cyclopentenones usually can be fabricated by Nazarov cyclization using divinyl ketones or functionalized tertiary divinyl carbinols(TDCs)as substrates.Ho...As one of the most common structural motifs in natural products,cyclopentenones usually can be fabricated by Nazarov cyclization using divinyl ketones or functionalized tertiary divinyl carbinols(TDCs)as substrates.However,straightforward method for transforming unfunctionalized TDCs to their corresponding cyclopentenones is currently lacking.Herein,we wish to report the total syntheses of four structurally distinct terpenoids,namely laurane-type marine sesquiterpenoids isolaurene,debromoaplysin and aplysin,and guaiane sesquiterpenoid guaiadienone A,all using a novel synthetic method,named oxidative Nazarov cyclization,as the key step.This work demonstrated our robust method is suitable for synthesizing various highly substituted cyclopentenones.展开更多
This review article summarizes the electron transfer reactions of piperidine aminoxyl radicals. Electrochemical studies revealed the single electron transfer nature of piperidine aminoxyl radicals. In solution, piperi...This review article summarizes the electron transfer reactions of piperidine aminoxyl radicals. Electrochemical studies revealed the single electron transfer nature of piperidine aminoxyl radicals. In solution, piperidine aminoxyl radicals serve as single electron transfer oxidation reagent to react with various biologically interesting molecules such as glutathione, cysteine, ascorbic acid, and amines. The reaction product distribution, reaction kinetics, intermediates, and the reaction features in biological mimic environments including micelles and cyclodextrins were investigated. Oxoammonium salts, the one-electron transfer oxidation products of piperidine aminoxyl radicals, are agents of organic synthesis to selectively generate ketones or di-ketones from alcohols or ketones bearing α-methylene group under mild conditions. The new reactions of oxoammonium salts with aromatic amines, phenols, heterocycles including phenothiazines, papaverine, and bilirubin are also illustrated.展开更多
An unprecedented decarboxylative alkylation reaction of fl-keto acids with isochromans has been developed under oxidative conditions. A range of β-keto acids smoothly undergo decarboxylative alkylation with isochroma...An unprecedented decarboxylative alkylation reaction of fl-keto acids with isochromans has been developed under oxidative conditions. A range of β-keto acids smoothly undergo decarboxylative alkylation with isochromans in the presence of 2,2,6,6-tetramethylpiperdine-1-oxoammonium hexafluorophosphate to give structurally diverse 1-acylmethylisochromans in moderate to excellent yields with extremely high regioselectivity.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘A facile method for the title transformation is described. The reaction of 2,2,6,6-tetramethyl-4-methoxypiperidine oxoammonium chloride (1b) and ketones bearing a-methylene group in acetonitrile proceeded smoothly to give the a-oxyfunctionalized coupling products (6a-h). These coupling products decomposed upon heating in acidic medium to produce a-diketones (7a-h) in good to excellent yields.
基金support from the National Natural Science Foundation of China(Nos.21971104,22001114 and 22271136)Shenzhen Science,Technology and Innovation Commission(JCYJ20220814203252001)+5 种基金Shenzhen Key Laboratory of Small Molecule Drug Discovery and Synthesis(ZDSYS20190902093215877)Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002)Guangdong Innovative Program(No.2019BT02Y335)Education Department of Guangdong Province,Key Research Projects in Colleges and Universities in Guangdong Province(2021ZDZX2035)Shenzhen Nobel Prize Scientists Laboratory Project(C17783101),Innovative Team of Universities in Guangdong Province(2020KCXTD016)Guangdong Natural Science Foundation(2022A1515010456)is greatly appreciated.
文摘As one of the most common structural motifs in natural products,cyclopentenones usually can be fabricated by Nazarov cyclization using divinyl ketones or functionalized tertiary divinyl carbinols(TDCs)as substrates.However,straightforward method for transforming unfunctionalized TDCs to their corresponding cyclopentenones is currently lacking.Herein,we wish to report the total syntheses of four structurally distinct terpenoids,namely laurane-type marine sesquiterpenoids isolaurene,debromoaplysin and aplysin,and guaiane sesquiterpenoid guaiadienone A,all using a novel synthetic method,named oxidative Nazarov cyclization,as the key step.This work demonstrated our robust method is suitable for synthesizing various highly substituted cyclopentenones.
基金supported by the National Natural Science Foundation of China
文摘This review article summarizes the electron transfer reactions of piperidine aminoxyl radicals. Electrochemical studies revealed the single electron transfer nature of piperidine aminoxyl radicals. In solution, piperidine aminoxyl radicals serve as single electron transfer oxidation reagent to react with various biologically interesting molecules such as glutathione, cysteine, ascorbic acid, and amines. The reaction product distribution, reaction kinetics, intermediates, and the reaction features in biological mimic environments including micelles and cyclodextrins were investigated. Oxoammonium salts, the one-electron transfer oxidation products of piperidine aminoxyl radicals, are agents of organic synthesis to selectively generate ketones or di-ketones from alcohols or ketones bearing α-methylene group under mild conditions. The new reactions of oxoammonium salts with aromatic amines, phenols, heterocycles including phenothiazines, papaverine, and bilirubin are also illustrated.
基金Acknowledgement We are grateful for the financial support from the National Natural Science Foundation of China （21232007 and 21172206）, the National Basic Research Program of China （973 Program 2010CB833300）, and the Program for Changjiang Scholars and Innovative Research Team in University （IRT1189）.
文摘An unprecedented decarboxylative alkylation reaction of fl-keto acids with isochromans has been developed under oxidative conditions. A range of β-keto acids smoothly undergo decarboxylative alkylation with isochromans in the presence of 2,2,6,6-tetramethylpiperdine-1-oxoammonium hexafluorophosphate to give structurally diverse 1-acylmethylisochromans in moderate to excellent yields with extremely high regioselectivity.
