Organocatalytic Asymmetric 1,6-Additions of -Ketoesters and Glycine Imine
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- 作者：Luca Bernardi ; Jesú ; s Ló ; pez-Cantarero ; Barbara Niess ; Karl Anker J<img src="http ; //pubs.acs.org/images/gifchars/oslash.gif" border="0">rgensen
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：May 2, 2007
- 年：2007
- 卷：129
- 期：17
- 页码：5772 - 5778
- 全文大小：137K
- 年卷期：v.129,no.17(May 2, 2007)
- ISSN：1520-5126
文摘
The first organocatalytic enantioselective 1,6-addition of <IMG SRC="/images/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-ketoesters and benzophenone imineto electron-poor 
-unsubstituted dienes using cinchona alkaloids under phase-transfer conditions isdemonstrated. The scope of the reaction for the 
-ketoesters is outlined for reactions with different-unsubstituted dienes having ketones, esters, and sulfones as electron-withdrawing substituents givingthe corresponding optically active products in good yields and enantioselectivities in the range of 90-99%ee. The 1,6-addition also proceeds with a number of cyclic -ketoesters having different ring sizes, ringsystems and substituents in high yields and enantioselectivities. The potential of this new organocatalytic1,6-addition for -ketoesters is demonstrated by a two-step synthesis of the bicyclo[3.2.1]octan-8-onestructure, a bicyclic bridged skeleton occurring in a variety of natural compounds. Benzophenone iminesalso undergo the organocatalytic asymmetric 1,6-addition to the activated dienes in high yields and withenantioselectivities from 92% to 98% ee, except in one case. The synthetic utility of this asymmetric reactionis demonstrated by the two-step transformation of the allylated 
-amino acid derivative to highly attractiveoptically active pyrrolidines.
-unsubstituted dienes using cinchona alkaloids under phase-transfer conditions isdemonstrated. The scope of the reaction for the -ketoesters is outlined for reactions with different-unsubstituted dienes having ketones, esters, and sulfones as electron-withdrawing substituents givingthe corresponding optically active products in good yields and enantioselectivities in the range of 90-99%ee. The 1,6-addition also proceeds with a number of cyclic -ketoesters having different ring sizes, ringsystems and substituents in high yields and enantioselectivities. The potential of this new organocatalytic1,6-addition for -ketoesters is demonstrated by a two-step synthesis of the bicyclo[3.2.1]octan-8-onestructure, a bicyclic bridged skeleton occurring in a variety of natural compounds. Benzophenone iminesalso undergo the organocatalytic asymmetric 1,6-addition to the activated dienes in high yields and withenantioselectivities from 92% to 98% ee, except in one case. The synthetic utility of this asymmetric reactionis demonstrated by the two-step transformation of the allylated -amino acid derivative to highly attractiveoptically active pyrrolidines.