De Novo Synthesis of Highly Functionalized Benzimidazolones and Benzoxazolones through an Electrochemical Dehydrogenative Cyclization Cascade
作者:Fan Xu、Hao Long、Jinshuai Song、Hai‐Chao Xu
DOI:10.1002/anie.201904931
日期:2019.7
benzoxazolone moieties are important scaffolds in a variety of pharmaceutical molecules. These bicyclic heterocycles are usually prepared from a benzene derivative through the construction of an additional five‐membered heterocyclic ring. We report herein a method that enables the efficient synthesis of highly substituted benzimidazolone and benzoxazolone derivatives by building both the benzene and the heterocyclic
N-Heterocyclic Carbene (NHC)-Catalyzed/Lewis Acid Mediated Conjugate Umpolung of Alkynyl Aldehydes for the Synthesis of Butenolides: A Formal [3+2] Annulation
作者:Jing Qi、Xingang Xie、Runfeng Han、Donghui Ma、Juan Yang、Xuegong She
DOI:10.1002/chem.201204386
日期:2013.3.25
Reverse to success! A new formal [3+2] annulation reaction combining alkynyl aldehydes and β,γ‐unsaturated α‐ketoesters has been disclosed by using a NHC‐catalyzed/Lewis acid mediated strategy. This cooperative catalysis strategy first allows the “allenolate” intermediate as a nucleophilic synthon at the β‐position to react with activated electrophilic reagents by an addition reaction as the key CC
Syntheses of <i>Z</i>-Iodovinylfurans and 2-Acyl Furans via Controllable Cyclization of Ynenones
作者:Mengxue Li、Fang Yang、Ting Yuan、Haoyang Li、Jian Li、Zi-Sheng Chen、Kegong Ji
DOI:10.1021/acs.joc.9b01852
日期:2019.10.4
Z-iodovinylfurans and 2-acyl furans promoted by NIS via controllable cyclization of ynenones is reported. The reaction proceeded by sequential 5-exo-dig electrophilic cyclization to intermediate 2-(iodomethylene)-2H-furanium cation D, providing a range of synthetically valuable and useful trisubstituted furan derivatives 2 and 3 in moderate to excellent yields. This approach is metal-free, mild, and atom-economic,
Asymmetric Protonation of Cumulenolates: Synthesis of Allenyl Aldehydes Facilitated by an Organomanganese Auxiliary
作者:Animesh Roy、Bilal A. Bhat、Salvatore D. Lepore
DOI:10.1021/acs.orglett.5b03681
日期:2016.3.18
Chiral ammonium salts were used to catalyze the isomerization of organomanganese-complexed alkynyl aldehydes to chiral allenal building blocks in moderate to good enantiomericexcesses. Normally, conjugated alkynyl aldehydes do not isomerize to their thermodynamically less stable allene isomers. However, with a manganese auxiliary in place to promote allene formation, asymmetric protonation of cumulenolate