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
One catalyst for two distinct reactions: sequential asymmetric hetero Diels–Alder reaction and diethylzinc addition
作者:Haifeng Du、Xue Zhang、Zheng Wang、Kuiling Ding
DOI:10.1016/j.tet.2005.08.007
日期:2005.10
addition to the benzaldehyde, affording the corresponding secondary alcohol with up to 94.5% ee under optimized conditions. On the basis of these facts, the integration of two distinct enantioselective reactions, HDA and diethylzincaddition reactions, has been realized in one-pot with the promotion of a single chiralzinc catalyst in a sequential manner. The impact of diimine additive on the catalytic system
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).
<i>cis</i>-2,5-Diaminobicyclo[2.2.2]octane, a New Scaffold for Asymmetric Catalysis via Salen−Metal Complexes
作者:James D. White、Subrata Shaw
DOI:10.1021/ol2007378
日期:2011.5.6
A new C2 symmetric salen scaffold based on cis-2,5-diaminobicyclo[2.2.2]octane has been synthesized that forms complexes with a wide range of metals. The chromium(III) complex is shown to catalyze the hetero-Diels−Alder reaction and the Nozaki−Hiyama−Kishi reaction with high efficiency and excellent stereoselectivity.