We report the synthesis of a versatile trifluoromethylsulfonamide calix[6]arenederivative with Brønsted acid features which can influence both molecular recognition and catalytic application. Indeed, in low polarity media, the trifluoromethyl-containing supramolecular wheel is able to respond to the complexation with charged species as a function of its selective ion-pair recognition. In parallel
Synthesis of 9,9′-biphenanthryl-10,10′-bis(oxazoline)s and their preliminary evaluations in the Friedel–Crafts alkylations of indoles with nitroalkenes
作者:Shuang-zheng Lin、Tian-pa You
DOI:10.1016/j.tet.2008.11.083
日期:2009.1
Chiral 9,9′-biphenanthryl-10,10′-bis(oxazoline)s 6a–d were firstly prepared. These new chiral compounds were evaluated as ligands for the Friedel–Craftsalkylations of indoles with nitroalkenes, excellent yields and modest to good enantioselectivities were achieved.
Silanediols: A New Class of Hydrogen Bond Donor Catalysts
作者:Andrew G. Schafer、Joshua M. Wieting、Anita E. Mattson
DOI:10.1021/ol2021115
日期:2011.10.7
Silanediols are introduced as a new class of hydrogenbond donor catalysts for the activation of nitroalkenes toward nucleophilic attack. Excellent yields of product are obtained for the conjugate addition of indole to β-nitrostyrene catalyzed with a stable, storable dinaphthyl-derived silanediol. The preparation and structural characterization of a C2-symmetric chiral silanediol is also reported along
Enantioselective Friedel−Crafts Alkylation of Indoles with Nitroalkenes Catalyzed by Bifunctional Tridentate Bis(oxazoline)−Zn(II) Complex
作者:Shao-Feng Lu、Da-Ming Du、Jiaxi Xu
DOI:10.1021/ol060586f
日期:2006.5.1
[reaction: see text] A more practical and efficient catalytic asymmetric Friedel-Craftsalkylation of indoles with nitroalkenes using bifunctional tridentate bis(oxazoline)-Zn(OTf)(2) as catalyst has been developed. Various types of the nitroalkylated indoles were obtained in excellent yields (85-99%) and high enantioselectivities (up to 98% ee).
Internal Lewis Acid Assisted Hydrogen Bond Donor Catalysis
作者:Sonia S. So、Julie A. Burkett、Anita E. Mattson
DOI:10.1021/ol102899y
日期:2011.2.18
Boronate ureas are introduced as a new class of noncovalent catalysts for conjugate addition reactions with enhanced activity. Through intramolecular coordination of the urea functionality to a strategically placed Lewis acid, rate enhancements up to 10 times that of more conventional urea catalysts are observed. The tunable nature of boronate ureas is a particularly attractive feature and enables the rational design of catalysts for optimal performance, in terms of both activity and stereocontrol, in new bond-forming processes.