Synthesis and resolution of new paramagnetic α-amino acids

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• 作者：Tamá ; s Ká ; lai ; Jó ; zsef Schindler ; Má ; ria Balog ; Elemé ; r Fogassy ; Ká ; lmá ; n Hideg
• 关键词：Amino acid ; Nitroxides ; O'Donnell reaction ; Pd-catalyzed cross-coupling ; Resolution
• 刊名：Tetrahedron
• 出版年：2008
• 期刊代码：107_00404020
• 类别：ch
• 出版时间：4 February 2008
• 卷：64
• 期：6
• 页码：1094-1100
• 文件大小：279 K

摘要

New, paramagnetic unnatural α-amino acids were synthesized by the O'Donnell method. In the new amino acids nitroxide is condensed with thiophene, benzene, and tetrahydroisoquinoline ring, or linked through a methylene, benzyl or propargyl spacer. Some of the racemic paramagnetic α-amino acid esters described earlier or in this work were resolved by fractional crystallization of diastereomeric salts. Another approach for optically active paramagnetic amino acids is the modification of S-tyrosine derivatives with Pd-catalyzed cross-coupling reactions with paramagnetic acetylene and with a paramagnetic boronic acid.