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Recently Developed Organometallic Complexes of Zn, Cu(Zn, Li), Fe, Ru and Less-used Ions. Use in Selective 1,2-or 1,4-Additions, Transfer Hydrogenations, Aldol Reactions and Diels-Alder Reactions

[ Vol. 2 , Issue. 4 ]

Author(s):

H. J. Zhu, J. X. Jiang, J. Ren, Y. M. Yan, C. U. Pittman and Jr.   Pages 547 - 587 ( 41 )

Abstract:


This review introduces the broad general topic of asymmetric organic synthetic reactions and reagents. Reagents containing both frequently used metallic ions, e.g. Zn++, Cu+(++) and Ru++, and rarely used ions, such as Ag+, employed in the construction of designed chiral centers, are updated here. Enantioselective 1,2-additions and 1,4-conjugate additions, transfer hydrogenations, and diasteroselective aldol reaction are discussed. The selectivities induced by chiral β-, δ- or γ-chiral amino alcohols, chiral diols, chiral binaphthyl derivatives, chiral P,N-containing auxiliaries, and other ligands used to prepare chiral metallic complexes, were compared in each reaction system. The use of two or more metallic ions with a single chiral ligand has now become a more popular strategy to catalyze chiral-center-controlled processes. For example, only diethylzinc was used in enantioselective additions to aldehydes in early studies. Recently, the combination of Et2Zn and Cu++ in the selective additions has been used to achieve high ee% values and yields. Finally, quantum calculations have been used to obtain kinetic data to predict a reactions ee% values. For example, the calculated δGcal. values have a strong relationship with the obtained δGfit values which have the direct linkage with the ee% values.

Keywords:

enantioselectivity, diastereoselectivity, conjugate addition, aldol reaction, hydrogenation, diels-alder

Affiliation:

State Key Lab ofPhyytochemistry and Plant Resources in West China, Kunming Institute ofBotany, CAS.



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