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,
Planarchiral 5,11‐disubstiuted dibenzo[a,e]cyclo‐octatetraenes (dbCOTs) have been developed as the first useful chiral homologs to dbCOT‐ligands for asymmetric applications. Methods enabling the preparation of such compounds on a gram‐scale in enantiomerically pure form are described. Evaluated as ligands in rhodium(I)‐catalyzed 1,4‐ and 1,2‐arylation reactions, tertiary and quarternary stereogenic
A Highly Efficient Friedel–Crafts Reaction of Tertiary α‐Hydroxyesters or α‐Hydroxyketones to α‐Quaternary Esters or Ketones
作者:Long Chen、Jian Zhou
DOI:10.1002/asia.201200693
日期:2012.11
A catalytic Friedel–Crafts arylation of α‐hydroxyesters or α‐hydroxyketones with electron‐rich aromatic compounds to furnish α‐quaternaryesters/ketones has been developed. The cheap and easy to handle catalyst HClO4 (70 %, aq) was identified as a powerful catalyst for this arylation reaction.
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
Metal-Free Tandem Friedel–Crafts/Lactonization Reaction to Benzofuranones Bearing a Quaternary Center at C3 Position
作者:Long Chen、Feng Zhou、Tao-Da Shi、Jian Zhou
DOI:10.1021/jo300395x
日期:2012.5.4
A metal-free tandem Friedel-Crafts/lactonization reaction to 3,3-diaryl or 3-alkyl-3-aryl benzofuranones catalyzed by HClO4 was reported. A variety of tertiary alpha-hydroxy acid esters could readily react with substituted phenols to afford the desired products in rich diversity. The synthetic utility of the products was demonstrated by the synthesis of polycyclic compounds. H-1 NMR studies supported that this tandem reaction proceeded via tandem Friedel-Crafts/lactonization sequence.