Novel open-chain and cyclic conformationally constrained (<i>R</i>)- and (<i>S</i>)-α,α-disubstituted tyrosine analogues
作者:Daniel Obrecht、Christian Lehmann、Ruth Ruffieux、Peter Schönholzer、Klaus Müller
DOI:10.1002/hlca.19950780613
日期:1995.9.20
structures are described (Figs. 1–4), showing β-turn type-I geometries for dipeptides 4a, 5b, and 4c and an extended conformation for peptide 5c (Table 3). The conversion of the free amino acids 1a–c into suitably protected building blocks 11a–d and 15d,e for peptide synthesis is discussed (Schemes 3 and 4).
合成了一系列新颖的开链和环状构象约束的(R)-和(S)-α,α-二取代的酪氨酸类似物1a-e,收率高,光学纯度高(方案1和2)。这些酪氨酸类似物的绝对构型是根据4型和5型前体非对映异构体肽的X射线结构明确确定的。描述了其中的四个结构(图1-4),显示了二肽4a,5b和4c的β-转角I型几何形状以及肽5c的扩展构象(表3))。讨论了将游离氨基酸1a-c转换成适当保护的结构单元11a-d和15d,e以进行肽合成的方法(方案3和4)。