EWG assisted nucleophilic fluorination using PPHF: a strategy for the synthesis of 1,2,2-triaryl-2-fluoroethanones
作者:Anil Kumar、Anil K. Pal、Rishi D. Anand、Tej V. Singh、Paloth Venugopalan
DOI:10.1016/j.tet.2011.08.083
日期:2011.10
The nucleophilic fluorination of 1,2,2-triaryl-2-hydroxyethanones by fluoride ion has been carried out usingpyridiniumpoly(hydrogenfluoride) (PPHF) to give 1,2,2-triaryl-2-fluoroethanones in fairly good yield. The presence of electron withdrawing group (EWG), such as –COAr at the carbon bearing hydroxyl group facilitates such nucleophilic fluorination. The intermediacy of bridged oxiranyl ion and
An efficient Fe(OTf)3-catalyzed nucleophilicsubstitution of cyclic or acyclic tertiary alcohols with difluoroenoxysilanes is developed, which provides a facile protocol for assembling structurally diverse α,α-gem-difluoroketones featuring a quaternary carbon center in good to excellent yields under mild conditions. Moreover, the diverse product elaborations highlight the utility of this protocol,
Metal-Free Azidation of α-Hydroxy Esters and α-Hydroxy Ketones Using Azidotrimethylsilane
作者:Xiao-Ping Yin、Lei Zhu、Jian Zhou
DOI:10.1002/adsc.201701345
日期:2018.3.20
We herein report a commercially available perchloric acid catalyst capable of catalyzing the azidation of α‐hydroxy esters, α‐hydroxy ketones and taddols using azidotrimethylsilane in dichloromethane at room temperature. Various substituted tertiary alcohols are well tolerated in this reaction. Cα‐tetrasubstituted α‐amino acidderivatives were prepared by one‐pot sequential azidation and hydrogenation
Regioselective Superacid-Catalyzed Electrocyclization of Diphenylmethyl Cations to Fluorenes, Phenanthrols and Benzofurans
作者:Tomohiko Ohwada、Naohiro Yoshida
DOI:10.1055/s-2001-16083
日期:——
Cationic electrocyclization of α-benzoyldiphenylmethanols in the presence of superacid provides fluorenes, phenanthrols and benzofurans in good to moderate yields. A single substitution leads to regioselective cationic electrocyclizations.