A Molecular Iodine-Mediated Synthesis of Cyclopenta[c]furo[3,2-b]furan-5,6-diones: Assembly of an Angular Dioxatriquinane Core
A molecular iodine-mediated synthesis of angular oxatriqinane core from 3-acetyl-2H-chromen-2-ones, β-bromo-β-nitrostyrenes, and pyridine in the presence of Et3N in MeCN containing a trace amount of water was developed. The reaction proceeds via intermolecular Michael reaction of 2-oxo-2-(2-oxo-2H-chromen-3-yl)-1-(pyridin-1-ium-1-yl)ethan-1-ide with bromonitrostyrene followed by intramolecular Michael reaction and elimination steps. Evidence for the stereochemistry of a typical product is obtained from single-crystal X-ray analyses. The important feature of this strategy is the fact that it forms three stereogenic centers with good selectivity.
Mohsenzadeh, Ramin,Ravaghi, Parisa,Yavari, Issa
p. 2616 - 2623
(2022/03/14)
Stereospecific approach to α,β-disubstituted nitroalkenes via coupling of α-bromonitroalkenes with boronic acids and terminal acetylenes
(Z)-α-Bromo-β-substituted nitroethylenes undergo facile Suzuki coupling with aryl, heteroaryl, and vinylboronic acids in the presence of Pd(PPh3)4 as catalyst to afford (E)-α,β-disubstituted nitroethylenes in high yield (up to 95%) and complete specificity. Similar coupling of α-bromonitroethylenes with terminal acetylenes (Sonogashira coupling) provides a novel route to (E)-nitroenynes. These Pd-catalyzed coupling methods offer a convenient and stereospecific entry into a diverse array of synthetically and biologically useful α,β-disubstituted nitroethylenes.
Ganesh, Madhu,Namboothiri, Irishi N.N.
p. 11973 - 11983
(2008/03/13)
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