<scp>L</scp>-Phenylalanine Cyclohexylamide: A simple and convenient auxiliary for the synthesis of optically pure α,α-disubstituted (<i>R</i>)- and (<i>S</i>)-amino acids
作者:Daniel Obrecht、Udo Bohdal、Clemens Broger、Daniel Bur、Christian Lehmann、Ruth Ruffieux、Peter Schönholzer、Clive Spiegler、Klaus Müller
DOI:10.1002/hlca.19950780305
日期:1995.5.10
synthesis of a series of optically pure α,α-disubstituted (R)- and (S)-amino acids of type 1, such as (R)- and (S)-2-methyl-phenylalanine (1a), (R)- and (S)-2-methyl-2-phenylglycine (1b), and (R)- and (S)-2-methylvaline (1c; Scheme 3). These amino acids were efficiently transformed into the suitably protected and activated amino acid building blocks (R)- and (S)-12b and (R)- and (S)-12c (Scheme 4) which are
这项工作描述了L-苯丙氨酸环己基酰胺(5C),其为简单的,价格便宜,且功能强大的手性助剂为一系列光学纯α,α-二取代的(的合成- [R )-和(小号)型的α-氨基酸1,这样如(R)-和(S)-2-甲基-苯丙氨酸(1a),(R)-和(S)-2-甲基-2-苯甘氨酸(1b)以及(R)-和(S)-2 -甲基缬氨酸(1c;方案3)。这些氨基酸被有效地转化为适当保护和活化的氨基酸构件(R)和(S)-12b以及(R)-和(S)-12c(方案4),它们已经准备好通过溶液或固相技术掺入肽中。基于属于非对映异构体肽系列6和7的6b,6c和7a的晶体结构,确定该系列的每个成员的绝对构型。对于6b和7a分别观察到II'和I型的β-转角几何形状,而6c以扩展构象结晶。讨论了侧链变化对这些三酰胺的构象和晶体堆积的影响。