Enantioselective Michael-type reaction of chiral linear α,α-disubstituted secondary enamines
摘要:
The enantioselective Michael-type reaction of chiral 2-substituted cyclic imines, reacting as their secondary enamine tautomers, has been extended to a linear ketimine possessing an oxo group on one of the substituents. A single secondary enamine tautomer is observed due to H-bonding of the NH group, thus allowing the reaction to proceed with a high degree of stereoselectivity.
A General and Efficient Method for the Preparation of β-Enamino Ketones and Esters Catalyzed by Indium Tribromide
作者:Zhan-Hui Zhang、Liang Yin、Yong-Mei Wang
DOI:10.1002/adsc.200505268
日期:2006.1
A variety of β-enaminoketones and esters have been synthesized in high to exellent yields by reacting β-dicarbonyl compounds with amines in the presence of a catalytic amount of indiumtribromide. The reaction proceeds smoothly at room temperature in a short reaction time under solvent-free conditions.
An Efficient Method for the Enamination of 1,3-Dicarbonyl Compounds with Ceric Ammonium Nitrate (CAN)
作者:Li-Ping Mo、Shu-Fen Liu、Wan-Zhi Li
DOI:10.1002/jccs.200700127
日期:2007.8
An efficient method for the enamination of 1,3-dicarbonylcompounds by employing ceric ammonium nitrate (CAN) as the catalyst has been described. A variety of β-amino-α,β-unsaturated ketones and esters have been synthesized in excellent yield within a short reaction time under solvent-free conditions.
Stereoselective Reduction of Enantiopure β-Enamino Esters by Hydride: A Convenient Synthesis of Both Enantiopure β-Amino Esters
作者:Cristina Cimarelli、Gianni Palmieri
DOI:10.1021/jo960107y
日期:1996.1.1
The reduction of enantiopure beta-enamino esters 1 with sodium triacetoxyborohydride in acetic acid is described. This occurs with good diastereo- and enantioselectivity to yield beta-amino esters 2 and 3 (after hydrogenolysis of the N-chiral group). A model is reported for the origin of the stereoselectivity through an enol ester-diacetoxyborohydride 6, which affords the intramolecular reduction. By choosing the appropriate chiral amine, this procedure allows a straightforward preparation of both the enantiopure beta-amino esters and derivatives with known biological activity, using readily available starting materials and inexpensive reagents and conditions.
Synthesis of Optically Active (+)-Canangone, Its 6-Epimer, and Determination of Absolute Configuration
The enantioselective Michael-type reaction of chiral 2-substituted cyclic imines, reacting as their secondary enamine tautomers, has been extended to a linear ketimine possessing an oxo group on one of the substituents. A single secondary enamine tautomer is observed due to H-bonding of the NH group, thus allowing the reaction to proceed with a high degree of stereoselectivity.