A series of dendritic substituted alkaloids, deriving from quinine or atropine and Frechet-type dendrons up to generation three, have been prepared. Enantioseparation of the dendronized atropine ammonium salts was achieved by HPLC on chiral stationary phases. Investigation of the chiroptical properties of the series of dendrimers by circulardichroism spectroscopy revealed an influence of the chiral
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
Supramolecular chiral dendritic monophosphites assembled by hydrogen bonding and their use in the Rh-catalyzed asymmetric hydrogenation
作者:Yong Li、Yan-Mei He、Zhi-Wei Li、Feng Zhang、Qing-Hua Fan
DOI:10.1039/b823047a
日期:——
A new type of supramolecular chiral dendritic monophosphite ligands has been prepared via a hydrogen-bonding assembly. The Rh complexes of these supramolecular ligands have been successfully applied in the asymmetric hydrogenation of enamides and dehydroamino acid derivatives with good enantioselectivities, which are comparable to those obtained from the free monophosphite ligands. The supramolecular catalyst could be easily recycled viasolvent precipitation.
Self-Assembly of Interlocked Supramolecular Dendrimers
作者:Kyu-Sung Jeong、Eun-Jin Park
DOI:10.1021/jo035798u
日期:2004.4.1
Interlocked supramoleculardendrimers were spontaneously self-assembledfrom molecular components, metallocycles, and dumbbells bearing benzyl ether repeating units. Here, the metallocycles were in situ self-assembledfrom L-shaped ligands with dendritic branches, 2,3-dimethyl-2-butene and osmium tetraoxide. The supramoleculardendrimers were stabilized by hydrogen-bonding interactions between the
Dendritic Chiral Phosphine Lewis Bases‐Catalyzed Asymmetric Aza‐Morita–Baylis–Hillman Reaction of
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‐Sulfonated Imines with Activated Olefins
作者:Ying‐hao Liu、Min Shi
DOI:10.1002/adsc.200700338
日期:2008.1.4
A series of polyether dendriticchiralphosphineLewisbases was synthesized, and successfully applied to the asymmetric aza-Morita–Baylis–Hillman reaction of N-sulfonated imines (N-arylmethylidene-4-methylbenzenesulfonamides) with methyl vinyl ketone (MVK), ethyl vinyl ketone (EVK), and acrolein to give the adducts in good to excellent yields along with up to 97 % ee, which are more effective than