Asymmetric synthesis of (5S)-4-deoxy-5-C-(4-nitrophenyl)-l-threo-pentose and (5R)-5-C-(4-nitrophenyl)-l-arabinose
摘要:
In the presence of Eu(fod)(3), (1E)-(2',3',4',6'-tetra-O-acetyl-beta-D-glucopyranosyloxy)buta-1,3-diene and its (3Z)-4-O-acetyl derivative undergo Re-face and endo selective hetero Diels-Alder reactions with 4-nitrobenzaldehyde, 5-nitrofuran-2-carbaldehyde and 5-nitrothiophene-2-carbaldehyde. The cycloadducts are converted into the title compounds, early examples of 'free' 5-C-arylpentopyranoses. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.
Evaluation of Catalyst Acidity and Substrate Electronic Effects in a Hydrogen Bond-Catalyzed Enantioselective Reaction
作者:Katrina H. Jensen、Matthew S. Sigman
DOI:10.1021/jo1013806
日期:2010.11.5
A modular catalyst structure was applied to evaluate the effects of catalystacidity in a hydrogen bond-catalyzed hetero Diels−Alder reaction. Linear free energy relationships between catalystacidity and both rate and enantioselectivity were observed, where greater catalystacidity leads to increased activity and enantioselectivity. A relationship between reactant electronic nature and rate was also
Assembled Dendritic Titanium Catalysts for Enantioselective Hetero-Diels–Alder Reaction of Aldehydes with Danishefsky's Diene
作者:Baoming Ji、Yu Yuan、Kuiling Ding、Jiben Meng
DOI:10.1002/chem.200305286
日期:2003.12.15
titanium-catalyzed hetero-Diels-Alderreaction of Danishefsky's diene with aldehydes. These reactions afforded the corresponding 2-substituted 2,3-dihydro-4H-pyran-4-ones in quantitative yields and with excellent enantioselectivities (up to 97.2 % ee). The disposition of the dendritic wedges and the dendron size in the ligands were found to have significant impact on the enantioselectivity of the reaction. The recovered
Asymmetric Hetero Diels-Alder Reaction Catalyzed by Chiral Ytterbium(III) Phosphate{Yb[(<i>R</i>)-(-)-BNP]<sub>3</sub>}: Remarkable Ligand Effect on the Enantioselectivity
作者:T. Hanamoto、H. Furuno、Y. Sugimoto、J. Inanaga
DOI:10.1055/s-1997-718
日期:——
2,6-Lutidine was found to be an effective additive for the chiral ytterbium(III) phosphate Yb[(R)-(-)-BNP]3}-catalyzed asymmetric hetero Diels-Alder reaction thus achieving high enantioselectivity (up to 93% ee) at room temperature.
1′-binaphthyl, and the structure was proved via X-ray analysis of its salicyl-aldehyde Schiff base, which was tested in the enantioselective titanium-catalyzed hetero-Diels-Alderreaction of Danishefsky’s diene with aldehydes. The reaction provided dihydropyranone in moderate to high yield (up to 99%) and enantioselectivities (up to 84.5% ee).
Design of Hydrogen Bond Catalysts Based on a Modular Oxazoline Template: Application to an Enantioselective Hetero Diels−Alder Reaction
作者:Sridhar Rajaram、Matthew S. Sigman
DOI:10.1021/ol052300x
日期:2005.11.1
[reaction: see text] A catalyst system that displays two hydrogenbond donating arms from a rigid oxazoline backbone and its utility in a hydrogenbond promoted enantioselective hetero Diels-Alderreaction are described.