A new chiral HBD system, N-tert-butyl sulfinyl squaramide, was designed and synthesized. The core N-tert-butyl sulfinyl squaramide with an 1-aminoindan-2-ol skeleton was found to be an efficient catalyst in the enantioselectiveFriedel–Craftsalkylation of indoles and acyl phosphonates.
Asymmetric Conjugate Addition of Silyl Enol Ethers Catalyzed by Tethered Bis(8-quinolinolato) Aluminum Complexes
作者:Norito Takenaka、Joshua P. Abell、Hisashi Yamamoto
DOI:10.1021/ja0668320
日期:2007.1.1
aluminum(III) complexes effectively catalyze the highly enantioselective Mukaiyama−Michael reaction of silyl enol ethers, including tetrasubstituted enolates that give rise to enantioenriched α-carbonyl all-carbon-substituted quaternary stereocenters. The present catalyst also promotes the conjugate addition of N-benzylindole to α,β-unsaturated acylphosphonates with high enantioselectivity (indole Friedel−Crafts
Catalytic Enantioselective Friedel-Crafts Alkylation of Indoles with β,γ-Unsaturated α-Keto Phosphonates in the Presence of Chiral Palladium Complexes
作者:Dae Kim、Young Kang、Ki Suh
DOI:10.1055/s-0030-1259932
日期:2011.5
The catalytic enantioselective Friedel―Crafts alkylation reaction promoted by chiralpalladium complexes is described. The treatment of indoles with β,γ-unsaturated α-ketophosphonates under the mild reaction conditions afforded the corresponding Friedel―Crafts alkylation adducts with excellent enantioselectivities (up to 99% ee).
Enantioselective Friedel−Crafts Alkylations Catalyzed by Bis(oxazolinyl)pyridine−Scandium(III) Triflate Complexes
作者:David A. Evans、Keith R. Fandrick、Hyun-Ji Song、Karl A. Scheidt、Risheng Xu
DOI:10.1021/ja072976i
日期:2007.8.1
The enantioselective Friedel-Crafts addition of a variety of indoles catalyzed by bis(oxazolinyl)pyridine-scandium(III) triflate complexes (Sc(III)-pybox) was accomplished utilizing a series of beta-substituted alpha,beta-unsaturated phosphonates and alpha,beta-unsaturated 2-acyl imidazoles. The acyl phosphonate products were efficiently transformed into esters and amides, whereas the acyl imidazole adducts were converted to a broader spectrum of functionalities such as esters, amides, carboxylic acids, ketones, and aldehydes. The sense of stereoinduction and level of enantioselectivity were found to be functions of the size of the substrate employed, the substitution on the ligand, and the catalyst loading. Molecular modeling of the catalyst with the bound substrates was performed based on the crystal structures of the catalyst complexes and the sense of stereoinduction observed in the addition reaction. Nonlinear effects over a range of catalyst concentrations implicate a mononuclear complex as the active catalyst.
Enantioselective Indole Friedel−Crafts Alkylations Catalyzed by Bis(oxazolinyl)pyridine−Scandium(III) Triflate Complexes
作者:David A. Evans、Karl A. Scheidt、Keith R. Fandrick、Hon Wai Lam、Jimmy Wu
DOI:10.1021/ja036985c
日期:2003.9.1
A highlyenantioselective Friedel-Crafts alkylation of electron-rich aromatic nucleophiles catalyzed by scandium(III) triflate-pyridyl(bis)oxazoline complexes has been accomplished. The reaction involves alpha,beta-unsaturated acyl phosphonates as electrophiles and primarily substituted indoles as nucleophiles. The reactive acyl phosphonate product is converted to the corresponding ester or amide in