114128-93-7Relevant academic research and scientific papers
Assignment of the Absolute Configuration of α-Chiral Carboxylic Acids by H NMR Spectroscopy
Ferreiro, Maria J.,Latypov, Shamil K.,Quinoa, Emilio,Riguera, Ricardo
, p. 2658 - 2666 (2000)
The prediction of the absolute configuration of α-chiral carboxylic acids from the 1H NMR spectra of their esters with (R)- and (S)-ethyl 2-hydroxy-2-(9-anthryl) acetate [(R)- and (S)-9-AHA, 5] is discussed. Low-temperature NMR experiments, MM, semiempirical, and aromatic shielding effect calculations allowed the identification of the main conformers and showed that, in all esters studied, conformer ap is the most stable. A simple model for the assignment of the absolute configuration from NMR data is presented, and its reliability is corroborated with acids 6-31 of known absolute configuration. In addition to 5, other auxiliary reagents with open (32-38) and cyclic (39-42) structures have also been studied. trans-(+)- and (-)-2-phenyl-1-cyclohexanol (41) was found to be particularly efficient and produced ΔδRS values similar to those of 5.
RESTRICTED ROTATION INVOLVING THE TETRAHEDRAL CARBON. L. ROTAMER DISTRIBUTIONS AND ROTATIONAL BARRIERS IN SOME 9-(1-METHOXYETHYL)TRIPTYCENE DERIVATIVES.
Tanaka,Yamamoto,Oki
, p. 3023 - 3027 (1983)
1,4-Dimethyl- and 1,2,3,4-tetrahalo-9-(1-methoxyethyl)triptycenes were synthesized by reactions of 9-(1-methoxyethyl)anthracene with appropriate benzynes. Rotamer distributions and rotational barriers about the bridgehead-to-substituent bond were studied by NMR spectroscopy. Rotamer distributions are governed mainly by the steric effect; the major rotamer is assigned to sc*(S*), the minor one to ap, and the third one found only in the tetrafluoro derivative to sc*(R*). *). Rotational barriers are 21-23 kcal mol** minus **1 which are slightly lower than those for the corresponding 9-isopropyltriptycenes.
Magnetic Resonance Study of Diastereomeric Interactions of Nitroaromatic Sulfoxides with Alcohols in Solution
Sweeting, Linda M.,Anet, Frank A. L.
, p. 539 - 542 (1984)
The synthesis of optically active (1R,2R)- and(1S,2R)-2-deutero-2,3-dihydro-2-methyl-6-nitrobenzothiophene-1-oxide (3 and 4) is described.Several racemic aryl methyl carbinols in the presence of 3 or 4 give different chemical shifts for enantiomeric CH, CH3 and OH protons.These chemical shift differences are larger than those observed in analogous sulfoxide-alcohol pairs without nitro groups.Quinine and cinchonidine cause observable non-equivalence of methylene and aromatic protons in racemic 4.The magnitude of the diastereomeric shift difference is sensitive to temperature, solvent, concentration, nature of the ? system and steric effects.
Establishing cleavage conditions for an anthracene chiral auxiliary using a photochemical retro Diels-Alder reaction
Atherton, J.C.Christian,Jones, Simon
, p. 9097 - 9100 (2002)
Photochemical Diels-Alder additions of chiral 9-anthranyl ethanol derivatives have been conducted giving rise to addition adducts in reasonable yield and excellent diastereoselectivity. Thermal and photochemical retro Diels-Alder additions have also been
Stereochemical sensitivity of the human UDP-glucuronosyltransferases 2B7 and 2B17
Bichlmaier, Ingo,Siiskonen, Antti,Finel, Moshe,Yli-Kauhaluoma, Jari
, p. 1818 - 1827 (2006)
A set of 28 enantiomers comprising rigid and flexible secondary alcohols was synthesized by the asymmetric Corey-Bakshi-Shibata reduction. The enantiomerically pure alcohols were subjected to enzymatic glucuronidation assays employing the human UDP-glucuronosyltransferases (UGTs) 2B7 and 2B17. Both UGTs displayed high levels of stereoselectivity, favoring the conjugation of the (R)-enantiomers over their respective (S)-stereoisomers at eudismic ratios up to 256. The spatial arrangement of the hydroxy group determined the diastereoselectivity of the UGT2B17-catalyzed reaction in agreement with Pfeiffer's rule (eudismic activity quotient = 0.83 ± 0.14). Inhibition studies revealed that the enantiomers had similar affinities toward the enzymes. The diastereoselectivity of the UGT-catalyzed conjugation stemmed, therefore, from the arrangement of the substrates in the catalytic site, rather than from distinct affinities toward the enzymes. Taken together, this study showed that metabolic enzymes that are generally conceived to be rather "flexible" in nature are capable of displaying high levels of chiral distinction.
Highly diastereoselective photochemical Diels-Alder reactions: Towards the development of a photoactivated chiral auxiliary
Jones, Simon,Atherton
, p. 1117 - 1119 (2001)
Photochemical Diels-Alder additions of maleic anhydride to a homochiral anthracene derivative occur with excellent diastereoselectivity (>95:5) and faster than the corresponding thermal reactions.
Diastereoselective cycloadditions and transformations of N -alkyl and N -aryl maleimides with chiral 9-anthrylethanol derivatives
Adams, Harry,Elsunaki, Tareg M.,Ojea-Jimenez, Isaac,Jones, Simon,Meijer, Anthony J. H. M.
, p. 6252 - 6262 (2010)
Figure presented. Thermal Diels-Alder reactions of chiral 9-methoxyethyl and 9-hydroxyethyl anthracene have been investigated both experimentally and computationally with a range of N-substituted maleimides. Whereas cycloadditions with 9-methoxyethyl anthracene proceeded with almost complete diastereselectivity, those with 1-anthracene-9-yl-ethanol resulted in essentially no diastereoselectivity. Subsequent regio- and stereoselective transformations with reducing agents and carbon nucleophiles demonstrated the synthetic utility of this methodology, which was applied to the enantioselective synthesis of pyrrolo[2,1-a]isoquinolines and an attempted synthesis of the alkaloid crispine A. Computational studies supported the proposed hypotheses for the stereoselectivity observed in the transformations described.
Preparation of 1-(9-anthryl)-ethanol and 9-anthryloxirane via catalytic enantioselective reduction of prochiral 9-anthryl ketones
Reiners,Martens
, p. 27 - 28 (1997)
Enantioselective reduction of prochiral 9-anthryl ketones to the corresponding chiral alcohols proceeds with high enantiomeric excess. The chiral alcohol 1-(9-anthryl)-2-bromo-ethanol can be converted to the corresponding chiral oxirane.
PQXdpap: Helical Poly(quinoxaline-2,3-diyl)s Bearing 4-(Dipropylamino)pyridin-3-yl Pendants as Chirality-Switchable Nucleophilic Catalysts for the Kinetic Resolution of Secondary Alcohols
Murakami, Ryo,Suginome, Michinori,Yamamoto, Takeshi
supporting information, p. 8711 - 8716 (2021/11/24)
Helically chiral poly(quinoxaline-2,3-diyl)s bearing 4-(dipropylamino)pyridin-3-yl pendants at the 5-position of the quinoxaline ring (PQXdpap) exhibited high catalytic activities and moderate to high selectivities (up to s = 87) in the acylative kinetic resolution of secondary alcohols. The solvent-dependent helical chirality switching of PQXdpap between pure toluene and a 1:1 mixture of toluene and 1,1,2-trichloroethane enabled the preparation of either compound of a pair of enantiomerically pure alcohols (>99% ee) from a single catalyst.
P-chirogenic Trost ligands mediated asymmetric hydrogenation of simple ketones
Du, Peng,Liu, Yan-Lan,Lu, Xiao-Bing
supporting information, (2020/09/22)
Herein, we report a highly active catalyst system consisting of (Rc,Rc,Rp,Rp)-P-chirogenic Trost ligand and [Ru(C6H6)Cl2]2 for asymmetric hydrogenation of simple ketones, affording the corresponding optically active alcohols in moderate enantioselectivity. A synergetic effect between P- and C-chirogenic centers of the P-chirogenic Trost ligands was observed in this asymmetric hydrogenation process.
