213990-63-7Relevant articles and documents
Enantioselective Copper Catalyzed Alkyne-Azide Cycloaddition by Dynamic Kinetic Resolution
Liu, En-Chih,Topczewski, Joseph J.
supporting information, p. 5135 - 5138 (2019/03/29)
The copper(I) catalyzed alkyne-azide cycloaddition (CuAAC), a click reaction, is one of the most powerful catalytic reactions developed during the last two decades. Conducting CuAAC enantioselectively would add a third dimension to this reaction and would
Ruthenium-catalyzed asymmetric epoxidation of olefins using H 2O2, part I: Synthesis of new chiral N,N,N,-tridentate pybox and pyboxazine ligands and their ruthenium complexes
Tse, Man Kin,Bhor, Santosh,Klawonn, Markus,Anilkumar, Gopinathan,Jiao, Haijun,Doebler, Christian,Spannenberg, Anke,Magerlein, Wolfgang,Hugl, Herbert,Beller, Matthias
, p. 1855 - 1874 (2008/02/02)
The synthesis of chiral tridentate N,N,N-pyridine-2.6-bisoxazolines 3 (pyhox ligands) and N,N,N-pyridine-2.6-bisoxazines 4 (pyboxazine ligands) is described in detail. These novel ligands constitute a useful tool-box for the application in asymmetric catalysis. Compounds 3 and 4 are conveniently prepared by cyclization of enantiomerically pure α- or β-amino al cohols with dimethyl pyridine-2,6-dicarboximidate. The corresponding ruthenium complexes are efficient asymmetric epoxidation catalysts and have been prepared in good yield and fully char acterized by spectroscopic means. Four of these ruthenium complexes have been characterized by X-ray crystallography. For the first time the molecular structure of a pyboxazine complex (2,6-bis-[(4S)-4-phenyl-5,6- dihydro-4H-[1,3]oxazinyl]pyridine)(pyridine-2,6-dicarboxylate)ruthenium (S)-2aa, is presented.
Asymmetric aminohydroxylation of substituted styrenes: Applications in the synthesis of enantiomerically enriched arylglycinols and a diamine
O'Brien, Peter,Osborne, Simon A.,Parker, Daniel D.
, p. 2519 - 2526 (2007/10/03)
The catalytic asymmetric aminohydroxylation of a variety of styrene derivatives and vinyl aromatics using osmium tetroxide in conjunction with alkaloid-derived ligands [e.g. (DHQ)2PHAL or (DHQD)2-PHAL] and haloamine salts of alkyl carbamates (e.g. ethyl carbamate or tert-butyl carbamate) has been investigated. By observing the effect of different aromatic substituents and alkyl carbamates on the regioselectivity, yield and enantioselectivity of the aminohydroxylation reactions, a number of conclusions have been reached: (i) the 1-aryl-2-hydroxyethylamine regioisomers were obtained as the major products in reasonable yield and high (≤87%) enantiomeric excess; (ii) tert-butyl carbamate was superior to ethyl carbamate in terms of yield, enantioselectivity and ease of removal of the N-protecting group; (iii) high (≥96%) enantioselectivity was observed with a 4-methoxy-substituted styrene whereas ortho-substituted styrenes gave lower enantioselectivities; (iv) chiral ligands (DHQ)2PHAL and (DHQD)2PHAL gave essentially equal and opposite senses and degrees of asymmetric induction; (v) regioselectivity was ligand dependent with better regioselectivity (and therefore higher isolated yields) obtained with (DHQ)2PHAL than with (DHQD)2PHAL. The products of the aminohydroxylation reactions were used to prepare enantiomerically enriched arylglycinols and a chiral diamine.
