2325-10-2Relevant academic research and scientific papers
A stereoselective, tandem [2+2] photocycloaddition-hydrolysis route to aldol-type adducts
Abe, Manabu,Ikeda, Masayuki,Nojima, Masatomo
, p. 3261 - 3266 (1998)
Photocycloadditions of aromatic aldehydes 2a-e with cyclic ketene silyl acetals 1a-e have been investigated. Regio-and exo-selective formation of the bicyclic 2-alkoxyoxetanes 3 was observed in high yields. Hydrolysis of the acid-labile oxetanes 3 with neutral water was efficiently achieved to give aldol-type adducts 4 (threo-selective formations).
A practical preparation of 4,4-diphenylcyclohexanol: A key intermediate in the synthesis of MS-325
Amedio Jr., John C.,Bernard, Paul J.,Fountain, Mark,Van Wagenen Jr., Gerritt
, p. 3895 - 3906 (1998)
A preparation of 4,4-diphenylcyclohexanol 2 is described from benzoin in five synthetic steps. The process uses readily available reagents and is suitable for manufacturing.
Catalytic asymmetric dihydroxylation of alkenes using silica gel supported cinchona alkaloid
Lohray,Nandanan,Bhushan, Vidya
, p. 2805 - 2808 (1996)
Immobilization of 3,6-bis(9-O-dihydroquinyl)pyridazine and 3,6-bis(9-O-dihydroquinidyl) pyridazine on silica gel support has been reported. The use of immobilized auxiliary has lead to comparable rate with that of the homogeneous catalytic AD of alkenes, however with lower ee.
Asymmetric pinacol coupling of aromatic aldehydes with TiCl2/enantiopure amine or hydrazine reagents
Enders, Dieter,Ullrich, Elke C.
, p. 3861 - 3865 (2000)
Asymmetric pinacol coupling of aromatic aldehydes under homogeneous conditions with TiCl2 in the presence of enantiopure amines or hydrazines afforded 1,2-diols in moderate to excellent yields with good dl-diastereoselectivities and enantioselectivities in the range of 6-65% ee. A non-linear temperature effect ('principle of isoinversion') has been examined. Copyright (C) 2000 Elsevier Science Ltd.
A free ligand for the asymmetric dihydroxylation of olefins utilizing one-phase catalysis and two-phase separation
Kuang, Yong-Qing,Zhang, Sheng-Yong,Jiang, Ru,Wei, Ling-Ling
, p. 3669 - 3671 (2002)
A free cinchona alkaloid derivative, which can be recovered and reused in the same way as the reported soluble polymer-supported cinchona alkaloid-derived ligands, was applied to the homogeneous asymmetric dihydroxylation of olefins. The molar ratio of ligand/olefin was 5%, being much lower than that required for the corresponding soluble polymer-supported ligands (10-25%). Yields of 82-93% and ees of 89-99% have been obtained.
On The Mechanism of Asymmetric Dihydroxylation(AD) of Alkenes
Lohray, Braj B.,Bhushan, Vidya,Nandanan, E.
, p. 4209 - 4210 (1994)
1H NMR studies on bis(9-O-dihydroquinidinyl)terephthalate (DHQD2-TP) with various concentration of osmium tetroxide and trans-3-hexene reveal that OsO4 is bound to both the quinuclidine moieties of DHQD2-TP but only one of the bound OsO4 reacts with alkenes in the AD process.
A novel chemoentrapment approach for supportless recycling of a catalyst: Catalytic asymmetric dihydroxylation
Lee, Daewon,Lee, Honggeun,Kim, Seyoung,Yeom, Chang-Eun,Kim, B. Moon
, p. 1021 - 1024 (2006)
A simple method of recycling a metal catalyst through chemoentrapment in an aqueous layer using ethyl vinyl ether has been developed. Using this new methodology, a highly efficient, filtration-free recycling of osmium for catalytic asymmetric dihydroxylation was accomplished. By means of the formation of a water-soluble OsO42- using EVE, AD reactions of mono- and disubstituted olefins with 1 mol % of OsO4 proceeded for up to 9 cycles without any loss of yields and enantioselectivities.
Asymmetric synthesis of β-amino alcohols by reductive cross-coupling of benzylideneamine with planar chiral benzaldehydes
Tanaka, Yoshie,Taniguchi, Nobukazu,Uemura, Motokazu
, p. 835 - 838 (2002)
(equation presented) Samarium iodide mediated reductive cross-coupling of N-tosyl benzylideneamine with benzaldehydes or the corresponding chromium complexes gave syn-β-amino alcohol derivatives. A dynamic kinetic resolution of a configurationally equilibrated reactive species occurred in the cross-coupling with planar chiral benzaldehyde chromium complexes.
Osmium-catalyzed asymmetric dihydroxylation of olefins using chiral isoxazolidine ligands
Imada,Saito,Kawakami,Murahashi
, p. 5081 - 5084 (1992)
Chiral isoxazolidines, which are readily obtained by 1,3-dipolar cycloadditions of nitrones with olefins, are found to be effective chiral ligands for osmium-catalyzed asymmetric dihydroxylations of olefins.
A New Crosslinked Polymer for the Heterogeneous Catalytic Asymmetric Dihydroxylation of Alkenes
Pini, Dario,Petri, Antonella,Salvadori, Piero
, p. 2351 - 2354 (1993)
Heterogeneous catalytic asymmetric dihydroxylation of alkenes has been reported using a new crosslinked polymer containing a cinchona alkaloid derivative.
