(+)- and (−)-2-Aminocyclobutane-1-carboxylic Acids and Their Incorporation into Highly Rigid β-Peptides: Stereoselective Synthesis and a Structural Study
作者:Sandra Izquierdo、Federico Rúa、Abdelouahid Sbai、Teodor Parella、Ángel Álvarez-Larena、Vicenç Branchadell、Rosa M. Ortuño
DOI:10.1021/jo0510843
日期:2005.9.1
Several derivatives of (+)- and (−)-2-aminocyclobutane-1-carboxylic acid, 1, have been prepared through enantiodivergent synthetic sequences. The stereoselective synthesis of free amino acid (+)-1 has been achieved, and this product has been fully characterized for the first time. Stereocontrolled alternative synthetic methodologies have been developed for the preparation of bis(cyclobutane) β-dipeptides
通过对映异构的合成序列已经制备了(+)-和(-)-2-氨基环丁烷-1-羧酸1的几种衍生物。立体选择性合成游离氨基酸(+)- 1已实现,并且此产品已首次全面表征。已经开发了立体控制的替代合成方法以高产率制备双(环丁烷)β-二肽。其中,已经合成了对映体和非对映体。还已经制备了由环丁烷残基和线性氨基酸的偶联产生的β,β-和β,δ-二聚体。已经显示出环丁烷环作为单体和二聚体中的结构促进单元的能力。NMR结构研究和DFT理论计算证明了强分子内分子的形成氢键产生顺式[4.2.0]辛烷结构单元,在溶液和气相中均赋予这些分子高刚性。还观察到了由围绕氨基甲酸酯NC(O)键旋转引起的顺式-反式构象平衡的贡献,反式是主要的构象体。在固态中,不存在该平衡,此外,存在分子间氢键。