Hypervalent Iodine(III) Reagents as Safe Alternatives to α-Nitro-α-diazocarbonyls
作者:Ryan P. Wurz、André B. Charette
DOI:10.1021/ol034672g
日期:2003.6.1
A cyclopropanation reaction involving iodonium ylides generated in situ allows for efficient preparation of substituted 1-nitro-1-carbonyl cyclopropanes. This robust cyclopropanation reaction can be performed in organic solvents, biphasic aqueous media, or under solvent-free conditions with alkene substrates. The iodonium ylides generated in situ display some surprising differences in reactivity when
Synthesis of -Nitro--diazocarbonyl Derivatives and Their Applications in the Cyclopropanation of Alkenes and in OH Insertion Reactions
作者:André B. Charette、Ryan P. Wurz、Thierry Ollevier
DOI:10.1002/hlca.200290023
日期:2002.12
a diazo-transfer reaction involving (trifluoromethyl)sulfonyl azide has been developed. These substrates undergo a rhodium-catalyzedcyclopropanation reaction with a variety of alkenes. A systematic study of the reaction indicated that the diastereoselectivity of the cyclopropanation could be effectively controlled through the modification of the steric bulk of the diazo reagent. A novel OH insertion
Organocatalytic conjugate addition of α-nitroacetates to β,γ-unsaturated α-keto esters and subsequent decarboxylation: synthesis of optically active δ-nitro-α-keto esters
作者:Rui-jiong Lu、Wen-tao Wei、Jin-jia Wang、Shao-zhen Nie、Xue-jing Zhang、Ming Yan
DOI:10.1016/j.tet.2012.09.014
日期:2012.11
Organocatalytic asymmetric conjugate addition of tert-butyl nitroacetates to β,γ-unsaturated α-keto esters has been developed. The subsequent in situ hydrolysis–decarboxylation of the adducts provided 5-nitro-2-oxopentanoates. A pyrrolidine-based thiourea-tertiary amine was identified as the best catalyst. A number of γ-aryl, γ-alkyl, and γ-heteroaryl β,γ-unsaturated α-keto esters and α-substituted
Methyl 2‐nitroacetate (MNA) is not as good as methyl acetoacetate (MAA) in giving transesterification reactions with alcohols. While MAA is capable of thermal transesterification without catalyst, MNA gives superior nitroacetates only with the use of a catalyst. Decomposition of MNA into CO2, CH3OH, and CH3NO2 should be prevented.
2-硝基乙酸甲酯(MNA)在与醇进行酯交换反应方面不如乙酰乙酸甲酯(MAA)好。尽管MAA能够在没有催化剂的情况下进行热酯交换,但MNA仅在使用催化剂的情况下才能提供优异的硝基乙酸酯。应防止MNA分解为CO 2,CH 3 OH和CH 3 NO 2。
Novel condensations of nitroacetic esters with aromatic aldehydes leading to 5-hydroxy-1,2-oxazin-6-ones
作者:Mikhail S. Baranov、Ilia V. Yampolsky
DOI:10.1016/j.tetlet.2012.11.132
日期:2013.2
the nature of the reagents in this new condensation were investigated. The data obtained suggest that the heterocyclic products 1 originate from intramolecular oxidation (similar to the Nef reaction) of dinitro derivative 2, followed by nucleophilic attack of the oxime oxygen at the carboxylate group. The condensation presented provides a novel general synthetic route to these types of heterocycle.