Mild and nonracemizing conditions for Ullmann-type diaryl ether formation between aryl iodides and tyrosine derivatives
Mild and nonracemizing conditions for Ullmann-type diaryl ether formation between aryl iodides and tyrosine derivatives
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DOI：
10.1021/jo0606960
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发表时间：
2006-07-07
影响因子：
3.6
通讯作者：
Ma, Dawei
中科院分区：
文献类型：
--
作者：
Cai, Qian;He, Gang;Ma, Dawei
[图解]CuI/N，N-二甲甘氨酸催化的L-酪氨酸衍生物和L-苯丙氨酸衍生的碘化物在90℃下在CS2CO3存在下发生偶联反应，提供相应的二芳基醚。当使用N-Boc和N-CBZ保护的芳香族氨基酸酯时，会发生部分外消旋，而N-三苯基和N，N-二苄基保护的芳香胺酯可以在不损失光学纯度的情况下产生偶联产物。在N-Boc和N-CBZ保护的芳香氨基酸作为底物的情况下，也观察到很少的外消旋。但他们的反应是温和的。在这些研究的基础上，开发了(S，S)-异剂量赖氨酸和K-13的较短组装方案。
[GRAPHICS]CuI/N,N-dimethylglycine-catalyzed coupling reaction of L-tyrosine derivatives and L-phenylalanine-derived iodides in the presence of Cs2CO3 works at 90 degrees C to provide the corresponding diaryl ether. Partial racemization occurs when N-Boc- and N-Cbz-protected aromatic amino esters are used, while N-trityl-and N,N-dibenzyl-protected aromatic amino esters give rise to coupling products without loss of optical purity. Little racemization is also observed in cases of N-Boc- and N-Cbz- protected aromatic amino acids as substrates. But their reaction yields are moderate. On the basis of these studies, shorter protocols for assembling (S,S)-isodityrosine and K-13 are developed.