Diphenylprolinol Methyl Ether: A Highly Enantioselective Catalyst for Michael Addition of Aldehydes to Simple Enones
作者:Yonggui Chi、Samuel H. Gellman
DOI:10.1021/ol0517729
日期:2005.9.1
[reaction: see text] Diphenylprolinol methyl ether catalyzes intermolecular Michaeladdition of simple aldehydes to relatively nonactivated enones with the highest enantioselectivities reported to date (95-99% ee) and significantly lower catalyst loadings than have been typical in this arena.
Enantioselective Organocatalytic Michael Additions of Aldehydes to Enones with Imidazolidinones: Cocatalyst Effects and Evidence for an Enamine Intermediate
作者:Timothy J. Peelen、Yonggui Chi、Samuel H. Gellman
DOI:10.1021/ja0532584
日期:2005.8.24
An enantioselective intermolecular Michaeladdition of aldehydes to enones catalyzed by imidazolidinones has been achieved. Chemoselectivity (Michaeladdition vs aldol) can be controlled through judicious choice of hydrogen-bond-donating cocatalysts. The optimal imidazolidinone/hydrogen-bond-donor pair affords Michaeladdition products in excess of 90% ee. Furthermore, we have isolated and characterized
已经实现了醛与由咪唑烷酮催化的烯酮的对映选择性分子间迈克尔加成。化学选择性(迈克尔加成与羟醛)可以通过明智地选择供氢键的助催化剂来控制。最佳咪唑烷酮/氢键供体对提供超过 90% ee 的迈克尔加成产物。此外,我们已经分离并表征了烯胺中间体,并证明了其在观察到的迈克尔加成反应中作为亲核试剂的功效。
A Rapid <sup>1</sup>H NMR Assay for Enantiomeric Excess of α-Substituted Aldehydes
作者:Yonggui Chi、Timothy J. Peelen、Samuel H. Gellman
DOI:10.1021/ol051174u
日期:2005.8.1
[GRAPHICS]In situ derivatization of a variety of alpha-substituted aldehydes via reaction with chiral amines allows convenient and efficient determination of enantiomeric excess. H-1 NMR analysis of the imine diastereomer ratio can be conducted immediately after the aldehyde and amine have been mixed. The results correlate well with ee values determined by more traditional (and slower) methods. This approach may be broadly applicable to alpha-substituted aldehydes.
Sebe; Naito, Taiwan Yaoxue Zazhi, 1950, vol. 2, p. 23,31
作者:Sebe、Naito
DOI:——
日期:——
Absolute configuration of the substituent at C-7 in guaiol