Asymmetric Synthesis of 3,4-Dihydrocoumarins Bearing an α,α-Disubstituted Amino Acid Moiety
作者:Joanna Hejmanowska、Anna Albrecht、Jakub Pięta、Łukasz Albrecht
DOI:10.1002/adsc.201500598
日期:2015.12.14
An organocatalytic approach for the stereoselective synthesis of 3,4-dihydrocoumarins with an α,α-disubstituted amino acid moiety incorporated is presented. The developed methodology is based on the cascade reaction between α-substituted azlactones and 2-hydroxychalcones. It is initiated by a chiral Brønsted base-catalyzed enantio- and diastereoselective Michael reaction followed by the azlactone ring
An Efficient One-Pot Synthesis of 1,2,3-Triazole-Fused Chromenes/Quinolines <i>via</i>
Oxidative [3+2] Cycloaddition followed by Reductive Cyclization
作者:D. Gangaprasad、J. Paul Raj、K. Karthikeyan、R. Rengasamy、J. Elangovan
DOI:10.1002/adsc.201800908
日期:2018.12.3
A convenient and efficient one‐pot synthesis of 1,2,3‐triazole‐fused chromenes/ quinolines is developed. The methodology is based on oxidative azide‐olefin [3+2] cycloaddition followed by intramolecular reductive cyclization. This methodology affords fast and simple access to 1,2,3‐triazole‐fused heterocycles in good to excellent yields without necessitating chromatographic purification.
A Pd(ii)-catalyzed asymmetric approach toward chiral [3.3.1]-bicyclic ketals using 2-hydroxyphenylboronic acid as a pro-bis(nucleophile)
作者:Feijun Wang、Feng Chen、Mingliang Qu、Teng Li、Yunlong Liu、Min Shi
DOI:10.1039/c3cc00295k
日期:——
Enantioselective Pd(II)-catalyzed construction of [3.3.1]-bicyclic ketals from 2-hydroxyphenylboronic acid 1 and enone 3 is reported, yielding enantioenriched [3.3.1]-bicyclic ketals in up to 97% yields and 98% ee.
preparation of optically active α-methylidene-δ-lactones is presented. The developed strategy utilizes an intramolecularRauhut–Currierreaction for a facile construction of the α-methylidene-δ-lactone framework. The reaction is catalyzed by a chiral phosphine and employs the principles of nucleophilic catalysis. It benefits from operational simplicity and uses readily available starting materials.
A combination of polarity reversal, Diels–Alder cycloaddition and skeletal remodeling to access pyridine-fused nitrones
作者:Huabin Han、Chaoyang Li、Xinyue Niu、Yuxia Wang、Wenjing Zhang、Qilin Wang
DOI:10.1039/d2cc00155a
日期:——
An unprecedented cascade strategy consisting of polarity reversal, normal electron-demand Diels–Alder cycloaddition and skeletal remodeling was developed to construct novel pyridine-fused nitrones in up to 82% yield. The key to the success was the umpolung process, which transformed the electron-deficient 3-nitropyridinium ring into a reactive, π-extended cyclic nitroalkene, serving as a rarely reported