Combining Fluorous and Triazole Moieties for the Tagging of Chiral Azabis(oxazoline) Ligands
作者:Ramesh Rasappan、Tobias Olbrich、Oliver Reiser
DOI:10.1002/adsc.200900129
日期:——
New fluorous-tagged azabis(oxazoline) ligands were prepared using the copper-catalyzed azide-alkyne cycloaddition as ligation method. The resulting ligands were tested in copper-catalyzed asymmetric benzoylations (up to 99% ee), nitroaldol (up to 90% ee), and Michael reactions (up to 82% ee). The combination of unpolar fluorinated alkyl chains and polar triazolemoieties imposes properties that are
Modification of Pseudo-C3-Symmetric Trisoxazoline and Its Application to the Friedel-Crafts Alkylation of Indoles and Pyrrole with Alkylidene Malonates
New pseudo-C3-symmetric hetero-trisoxazoline can be easily prepared on a gram scale in good yield. Its combination with copper(II) triflate exhibits high enantiomeric induction in the asymmetric Friedel-Crafts alkylation between indoles and alkylidene malonates, with up to 97% ee and good to excellent yields. The catalyst loading can be lowered to 0.5 mol% without loss of the enantiomeric excess.
Sidearm Effect: Improvement of the Enantiomeric Excess in the Asymmetric Michael Addition of Indoles to Alkylidene Malonates
作者:Jian Zhou、Yong Tang
DOI:10.1021/ja026936k
日期:2002.8.1
A pseudo-C3-trisoxazoline was designed and synthesized. The improvement of the traditional bisoxazoline into a novel trisoxazoline by a sidearm approach resulted in highly catalytic enantioselective Michael addition of indoles to alkylidene malonates. Excellent catalytic reactivity and enantioselectivity (up to 99% yield and 93% ee) were achieved.
Enantioselective Friedel–Crafts reaction of indoles with arylidene malonates catalyzed by<sup>i</sup>Pr-bisoxazoline–Cu(OTf)<sub>2</sub>
作者:Jian Zhou、Yong Tang
DOI:10.1039/b313197a
日期:——
The cheap and simple iPr-bisoxazolineâCu(OTf)2 proves to be an efficient catalyst in the asymmetric FriedelâCrafts reaction of indole with arylidene malonates. In iBuOH, the S-enantiomer was obtained in up to 97% ee, while the opposite enantiomer was obtained in up to 78% ee in CH2Cl2 or TTCE.
Malonate-type bis(oxazoline) ligands with sp2 hybridized bridge carbon: synthesis and application in Friedel–Crafts alkylation and allylic alkylation
作者:Hongliang Chen、Fengpei Du、Lei Liu、Jing Li、Qiuying Zhao、Bin Fu
DOI:10.1016/j.tet.2011.09.106
日期:2011.12
the Friedel–Crafts reaction and allylicalkylation. The Cu(II) complex of ligand 4b bearing the benzyl group afforded good to excellent enantioselectivity for the F–C adducts (up to >99% ee) between indole and alkylidene malonate, and the palladium complex of ligand 4c bearing the phenyl group afforded excellent enantioselectivity (up to 94% ee) for the allylicalkylation product.