A Practical and Convenient Protocol for the Synthesis of (<i>E</i>)-α,β-Unsaturated Acids
作者:Amar R. Mohite、Ramakrishna G. Bhat
DOI:10.1021/ol402130t
日期:2013.9.6
α,β-Unsaturated acids are very useful and versatile reagents in organic synthesis. A novel, practical, and convenient catalytic protocol comprising FeCl3·6H2O (0.5 mol %) and H2O (1 equiv) in CH3NO2 is described for the rapid synthesis of α,β-unsaturated acids with high E-stereoselectivity under both microwave and conventional heating conditions with high TON and TOF values. This powerful approach
Sc(OTf)<sub>3</sub>-Catalyzed Conjugate Allylation of Alkylidene Meldrum’s Acids
作者:Aaron M. Dumas、Eric Fillion
DOI:10.1021/ol9003959
日期:2009.5.7
Alkylidene Meldrum’s acids are allylated in a conjugate fashion by allyltin nucleophiles under mild Sc(OTf)3-catalyzed conditions. The addition is functional group tolerant and reactions with nonracemic alkylidenes are highlydiastereoselective. Allylation of alkylidenes derived from α-ketoesters yield all-carbon quaternary stereocenters.
Stereoselective Sequential Spirocyclopropanation/Cloke–Wilson Rearrangement Reactions for Synthesis of <i>trans</i>-β,γ-Disubstituted γ-Butyrolactones Using Alkylidene Meldrum’s Acid and Benzyl Halides
spirocyclopropanation/Cloke-Wilson rearrangement reactions have been developed to synthesize γ-butyrolactones using alkylidene Meldrum's acids and benzyl halides. The DBU-promoted spirocyclopropanation was carried out efficiently at room temperature to generate trans-isomeric spirocyclopropyl Meldrum's acid, and the following stereospecific thermal decarboxylative Cloke-Wilson rearrangement afforded trans-γ-butyrolactones
Practical Asymmetric Conjugate Alkynylation of Meldrum’s Acid-Derived Acceptors: Access to Chiral β-Alkynyl Acids
作者:Sheng Cui、Shawn D. Walker、Jacqueline C. S. Woo、Christopher J. Borths、Herschel Mukherjee、Maosheng J. Chen、Margaret M. Faul
DOI:10.1021/ja909105s
日期:2010.1.20
The enantioselective conjugate addition of alkynyl nucleophiles has been a long-standing challenge in synthetic chemistry. This paper describes a highly practical asymmetricconjugatealkynylation of Meldrum's acid-derived acceptors using cinchonidine (<$100/kg) as the chiral mediator. The process provides practical access to chiral beta-alkynyl acids. Noteworthy attributes of the method are its broad
Self-Assembled Pd<sub>6</sub>Open Cage with Triimidazole Walls and the Use of Its Confined Nanospace for Catalytic Knoevenagel- and Diels-Alder Reactions in Aqueous Medium
作者:Dipak Samanta、Sandip Mukherjee、Yogesh P. Patil、Partha Sarathi Mukherjee
DOI:10.1002/chem.201201679
日期:2012.9.24
the formation of a water‐soluble semi‐cylindrical cage with a hydrophobiccavity, which was separately crystallized with hydrophilic‐ and hydrophobic guests. The parent cage was found to catalyze the Knoevenagel condensation reaction of a series of aromatic mono‐aldehydes with active methylene compounds, such as Meldrum′sacid or 1,3‐dimethylbarbituric acid. The confined hydrophobic nanospace within