1207620-66-3Relevant academic research and scientific papers
Chiral ethylene-bridged flavinium salts: the stereoselectivity of flavin-10a-hydroperoxide formation and the effect of substitution on the photochemical properties
?urek, Ji?í,Svobodová, Eva,?turala, Ji?í,Dvo?áková, Hana,Svoboda, Ji?í,Cibulka, Radek
, p. 1780 - 1791 (2017/11/17)
A series of chiral non-racemic N1,N10-ethylene bridged flavinium salts 4 was prepared using enantiomerically pure 2-substituted 2-aminoethanols (R = isopropyl, phenyl, benzyl, 4-methoxybenzyl, 4-benzyloxybenzyl) derived from amino acids as the sole source of chirality. The flavinium salts were shown to form 10a-hydroperoxy- and 10a-methoxy-adducts with moderate to high diastereoselectivity depending on the ethylene bridge substituent originating from the starting amino acid. High diastereoselectivities (dr values from 80:20 to >95:5) were observed for flavinium salts bearing benzyl substituents attached to the ethylene bridge. The benzyl group preferred the face-to-face (syn) orientation relative to the flavinium unit; thereby effectively preventing nucleophilic attack from one side. This conformation was found to be the most stable according to the DFT calculations. Consequently, the presence of benzyl groups causes intermolecular fluorescence quenching resulting in a significant decrease in the fluorescence quantum yield from 11% for 4a bearing an isopropyl substituent to 0.3% for 4c containing a benzyl group and to a value lower than 0.1% for the benzyloxybenzyl derivative 4e.
Facile synthesis of chiral benzimidazolium salts and the application in asymmetric catalytic borylation
Zhou, Jie,Liu, Xiaohui,Sun, Zhihua
, p. 944 - 953 (2016/07/06)
A synthetic method towards chiral benzimidazolium salts is developed. The stereocenter is introduced by direct aromatic substitution of 2-fluoronitrobenzene with optically pure amines. After nitro group reduction, selective arylation of the primary amine is achieved via copper catalyzed Chan-Lam coupling reaction. Finally, cyclization of the diamine with HC(OMe)3 afforded the desired chiral benzimidazolium salts. In situ generated benzimidazole carbenes show potential application for asymmetric catalytic borylation of α,β-unsaturated esters, providing up to 85% ee value with a catalyst loading of only 0.5 mol%.
A trifluoroacetic acid catalyzed domino reaction as an approach to amino acid derived 2,3-dihydro-1 H -1,5-benzodiazepines
Bera, Saurav,Kandiyal, Pancham S.,Ampapathi, Ravi S.,Panda, Gautam
, p. 939 - 944 (2014/05/06)
Trifluoroacetic acid catalyzed condensation of aromatic amines with substituted benzaldehydes followed by intramolecular cyclization furnishes a highly effective synthesis of amino acid derived 2,3-dihydro-1H-1,5- benzodiazepines. The strategy provides an
Asymmetric hydrogenation of quinoxalines, benzoxazines, and a benzothiazine catalyzed by chiral ruthenabicyclic complexes
Arai, Noriyoshi,Saruwatari, Yu,Isobe, Kotaro,Ohkuma, Takeshi
, p. 2769 - 2774 (2014/03/21)
The ruthenabicyclic complex RuCl[(R)-daipena][(R)-dm-segphos] with potassium tert-butoxide catalyzes the hydrogenation of 2-alkylquinoxalines and a 3-methyl-2H-1,4-benzoxazine in toluene under 20-100 atm of hydrogen at 40 °C to afford S-configured cyclic
Inter- and intramolecular Mitsunobu reaction and metal complexation study: Synthesis of S-amino acids derived chiral 1,2,3,4-tetrahydroquinoxaline, benzo-annulated [9]-N3 peraza, [12]-N4 peraza-macrocycles
Samanta, Krishnananda,Srivastava, Nitin,Saha, Satyen,Panda, Gautam
, p. 1553 - 1564 (2012/03/22)
Substituted 1,2,3,4-tetrahydroquinoxaline, benzo-annulated unsymmetrical chiral [9]-N3 peraza, and [12]-N4 peraza-macrocycles have been synthesized employing an inter- and intramolecular Mitsunobu reaction from an amino acid derived
Design of chiral hydroxyalkyl- and hydroxyarylazolinium salts as new chelating diaminocarbene ligand precursors devoted to asymmetric copper-catalyzed conjugate addition
Rix, Diane,Labat, Stephane,Toupet, Loic,Crevisy, Christophe,Mauduit, Marc
scheme or table, p. 1989 - 1999 (2009/10/30)
The design and the synthesis of a set of new chiral hy- droxyalkyl- and hydroxyaryl-chelating diaminocarbene ligands is reported. Comparative catalytic studies show the importance of the scaffold design around the NHC unit to obtain a high enantiocontrol in Cu-catalyzed asymmetric conjugate addition (ACA). Whereas low selectivities are observed when the stereogenic centre is placed within the N-heterocyclic ring, an interesting match effect can be observed when central chirality is located within both of the two side chains, which enables up to 92 % ee in the catalysis reaction. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009.
