871730-96-0Relevant academic research and scientific papers
Exploiting the chiral ligands of bis(Imidazolinyl)-and bis(oxazolinyl)thiophenes—Synthesis and application in Cu-catalyzed friedel–crafts asymmetric alkylation
Al-Majid, Abdullah Mohammed,Alammari, Abdullah Saleh,Alshahrani, Saeed,Barakat, Assem,Haukka, Matti,Islam, Mohammad Shahidul
, (2021/12/17)
Five new C2-symmetric chiral ligands of 2,5-bis(imidazolinyl)thiophene (L1–L3) and 2,5-bis(oxazolinyl)thiophene (L4 and L5) were synthesized from thiophene-2,5-dicarboxylic acid (1) with enantiopure amino alcohols (4a–c) in excellent optical purity and chemical yield. The util-ity of these new chiral ligands for Friedel–Crafts asymmetric alkylation was explored. Subse-quently, the optimized tridentate ligand L5 and Cu(OTf)2 catalyst (15 mol%) in toluene for 48 h promoted Friedel–Crafts asymmetric alkylation in moderate to good yields (up to 76%) and with good enantioselectivity (up to 81% ee). The bis(oxazolinyl)thiophene ligands were more potent than bis(imidazolinyl)thiophene analogues for the asymmetric induction of the Friedel–Crafts asymmetric alkylation.
Enantioselective Friedel-Crafts alkylation of indole with nitroalkenes in the presence of bifunctional squaramide organocatalysts
Dündar, Esra,Tanyeli, Cihangir
supporting information, (2021/05/26)
A series of chiral bifunctional quinine and 2-aminoDMAP based squaramide organocatalysts are evaluated in Friedel-Crafts alkylation of indoles with nitroolefins. These 3-substituted indole derivatives are synthesized in the presence of sterically encumber
A chiral bicyclic skeleton-tethered bipyridine-Zn(OTf)2 complex as a Lewis acid: Enantioselective Friedel-Crafts alkylation of indoles with nitroalkenes
Venkatanna, Kesa,Yeswanth Kumar, Santhakumar,Karthick, Muthupandi,Padmanaban, Ramanathan,Ramaraj Ramanathan, Chinnasamy
, p. 4077 - 4086 (2019/04/30)
A conformationally rigid chiral bicyclic skeleton tethered bipyridine-Zn(OTf)2 complex facilitated the enantioselective Friedel-Crafts alkylation of indoles with trans-β-nitroarylalkenes in an enantioselective manner at elevated temperature. Indoles reacted smoothly with β-nitroarylalkenes to generate the corresponding 3-(2-nitroalkyl)indoles in good to excellent yields (up to 94%) with moderate to excellent enantioselectivities (up to 91%). The stereochemical outcome of the product from indole and trans-β-nitrostyrene in the presence of the CRCB tethered bipyridine-Zn(OTf)2 complex and the DFT calculation of the CRCB tethered bipyridine-Zn:trans-β-nitrostyrene complex support the si-face attack of indole on trans-β-nitrostyrene.
Electrostatically enhanced phosphoric acids and their applications in asymmetric friedel-crafts alkylations
Ma, Jie,Kass, Steven R.
, p. 11125 - 11134 (2019/09/10)
A series of electrostatically enhanced phosphoric acid catalysts were synthesized and studied. These compounds possess two positively charged N-octylpyridinium or triarylphosphonium ion centers at the 3,3′-positions of the (R)-BINOL backbone to enhance re
Enantioselective Friedel-Crafts Alkylation between Nitroalkenes and Indoles Catalyzed by Charge Activated Thiourea Organocatalysts
Fan, Yang,Kass, Steven R.
, p. 13288 - 13296 (2017/12/26)
A series of methylated and octylated pyridinium and quinolinium containing thiourea salts with a chiral 2-indanol substituent are reported. These organocatalysts are positively charged analogues of privileged bis(3,5-trifluoromethyl)phenyl substituted thi
Synthesis of chiral benzene-based tetraoxazolines and their application in asymmetric Friedel-Crafts alkylation of indole derivatives with nitroalkenes
Li, Wei-Jie
, p. 53 - 56 (2014/06/09)
A series of new chiral benzene-based tetraoxazoline ligands were prepared in good yields through the reaction of 1,2,4,5-benzenetetracarboxylic acid and chiral β-amino alcohols by continuous removal of water, and the asymmetric Friedel-Crafts alkylation of indole derivatives with nitroalkenes was tested using the chiral catalysts, which were generated in situ by refluxing the above ligands and anhydrous zinc chloride in solvent. In most case, good yields (up to 99%) and excellent enantioselectivities (up to 98% ee) were obtained.
A new type of bis(sulfonamide)-diamine ligand for a Cu(OTf) 2-catalyzed asymmetric friedel-crafts alkylation reaction of indoles with nitroalkenes
Wu, Jing,Li, Xincheng,Wu, Fan,Wan, Boshun
supporting information; experimental part, p. 4834 - 4837 (2011/11/14)
Chiral bis(sulfonamide)-diamine served as new type of ligand for a Cu(OTf)2-catalyzed asymmetric Friedel-Crafts alkylation reaction of indoles with nitroalkenes. The desired products were obtained with up to 99% yield and 97% ee.
Immobilization of diphenylamine-linked bis(oxazoline) ligands and their application in the asymmetric friedel-crafts alkylation of indole derivatives with nitroalkenes
Liu, Han,Du, Da-Ming
supporting information; experimental part, p. 2121 - 2131 (2010/06/15)
A diphenylamine-linked bis(oxazoline) ligand with trans-diphenyl substitution on the oxazoline rings has been immobilized onto one- to three-generation Frechet-type dendrimers and a C3-symmetric core structure. The catalytic activities and enantioselectivities of these new ligands were tested in the asymmetric Friedel-Crafts alkylation reactions of indole derivatives with, nitroalkenes. The two types of immobilized ligands exhibited similar enantioselectivities and substrate compatibilities to the free ligand trans-DPBO we reported previously. No dendrimer effect was observed in the kinetic investigation of the Frechet-type dendrimer-immobilized ligands. The in situ recycling of the catalysts was also tested to illustrate the effect of reducing catalyst loading and the efficiency of our system.
Development of diphenylamine-linked bis(imidazoline) ligands and their application in asymmetric Friedel-Crafts alkylation of indole derivatives with nitroalkenes
Liu, Han,Du, Da-Ming
experimental part, p. 1113 - 1118 (2010/07/03)
The new diphenylamine-linked bis(imidazoline) ligands were prepared through Kelly-You's imidazoline formation procedure mediated by Hendrickson 's reagent in good yields. The novel ligands were tested in the asymmetric Friedel-Crafts alkylation of indole derivatives with nitroalkenes. In most cases, good yields (up to 97%) and excellent enantioselectivities (up to 98%) can be achieved. The optimized bis(imidazoline) ligand with trans-diphenyl substitution on the imidazoline ring gave better enantioselectivity than the corresponding bis(oxazoline) ligand.
