Entry to New Conformationally Constrained Amino Acids. First Synthesis of 3-Unsubstituted 4-Alkyl-4-carboxy-2-azetidinone Derivatives via an Intramolecular <i>N</i><sup>α</sup><i>-C</i><sup>α</sup>-Cyclization Strategy
作者:Guillermo Gerona-Navarro、Maria Angeles Bonache、Rosario Herranz、Maria Teresa García-López、Rosario González-Muñiz
DOI:10.1021/jo015559b
日期:2001.5.1
N-benzyl-N-chloroacetyl amino acid derivatives is described. This study resulted in the first concise and versatile route to the preparation of 3-unsubstituted 4-alkyl-4-carboxy-2-azetidinones, to be included into the scarce family of beta-lactams with quaternary centers at the C(4) position. Particularly noteworthy is that the intramolecular N(alpha)-C(alpha)-cyclization of Phe and Leu derivatives afforded the
描述了N-苄基-N-氯乙酰基氨基酸衍生物的碱基辅助分子内烷基化的系统研究。这项研究导致了第一个简洁而通用的制备3-未取代的4-烷基-4-羧基-2-氮杂环丁酮的方法,该方法将被包括在稀有的β-内酰胺类家族中,其四元中心在C(4)位置。特别值得注意的是,Phe和Leu衍生物的分子内Nα-Cα-环化作用提供了具有中等对映选择性(最高56%)的相应β-内酰胺衍生物。建议在这些特殊情况下,通过具有动态手性的平面烯醇中间体进行环化反应。所描述的反应顺序,与常用的α-羧基保护基团相容,