Modular peptide-based phosphine ligands-in asymmetric catalysis: Efficient and enantioselective Cu-catalyzed conjugate additions to five-, six-, and seven-membered cyclic enones
Modular peptide-based phosphine ligands-in asymmetric catalysis: Efficient and enantioselective Cu-catalyzed conjugate additions to five-, six-, and seven-membered cyclic enones
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DOI：
10.1021/ja003698p
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发表时间：
2001-01-31
影响因子：
15
通讯作者：
Hoveyda, AH
中科院分区：
文献类型：
--
作者：
Degrado, SJ;Mizutani, H;Hoveyda, AH
基于多肽的催化剂在不对称转化的发展中提供了有吸引力和实用的选择。多肽很容易制备，由容易获得的手性构建块组成，并且是模块化的。在很大程度上由于这些吸引人的属性，金属多肽配合物最近被证明启动了不对称CC键的形成反应。1这些实验室的研究，包括以多肽为基础的酚类席夫碱作为手性配体(例如，1，方案1)，导致了钛催化的TMSCN与介孔环氧化物的加成2和亚胺(Strecker氨基酸合成)，3和二烷基锌与亚胺的催化加成。4多肽配体在上述程序中的有效性使我们研究了它们在催化与烷基金属的对映选择性烯烃烷基化反应中的作用。本文报道了二烷基锌试剂与环烯酮的催化对映选择性共轭加成反应的研究结果。6，7这些转化是由(CuOTf)2，C6H6与基于多肽的手性膦配体(2，方案1)共同促进的。8所描述的方法不仅允许六元和七元环烯酮的高效、催化和高对映选择性(>；95%ee)官能化，而且还允许环戊酮的官能化。值得注意的是，烷基金属与五元环烯酮的催化不对称共轭加成反应的效率和选择性明显低于较大环类似物的反应。7.
Peptide-based catalysts offer attractive and practical options in the development of asymmetric transformations. Peptides are easily prepared, consist of readily available chiral building blocks and are modular. Largely due to these attractive attributes, metalpeptide complexes have recently been demonstrated to initiate asymmetric CC bond forming reactions. 1 Research in these laboratories, involving peptide-based phenolic Schiff bases as chiral ligands (eg, 1, Scheme 1), has led to the development of Ti-catalyzed additions of TMSCN to meso epoxides2 and imines (Strecker amino acid synthesis), 3 and Zr-catalyzed addition of dialkylzincs to imines. 4 The effectiveness of peptidic ligands in the aforementioned programs led us to investigate their utility in promoting catalytic enantioselective olefin alkylations with alkylmetals. 5Herein, we report the results of our studies on catalytic enantioselective conjugate addition of dialkylzinc reagents to cyclic enones. 6, 7 These transformations are promoted by (CuOTf) 2 ‚C6H6 in conjunction with peptide-based chiral phosphine ligands (2, Scheme 1). 8 The method described allows for efficient, catalytic, and highly enantioselective (> 95% ee) functionalization of not only six-and seven-membered ring enones, but also of cyclopentenones. It is worth noting that the catalytic asymmetric conjugate addition of alkylmetals to five-membered ring enones has previously been shown to be significantly less efficient and selective than reactions of the larger ring analogues. 7