Synthesis of 1,4-Oxazepane-2,5-diones via Cyclization of Rotationally Restricted Amino Acid Precursors and Structural Reassignment of Serratin
作者:Ewout Ruysbergh、Kristof Van Hecke、Christian V. Stevens、Norbert De Kimpe、Sven Mangelinckx
DOI:10.1021/acs.joc.7b00790
日期:2017.6.16
trans-conformation, and the presence of a labile lactone in this core, many synthetic methodologies commonly used for the cyclization toward medium-sized heterocycles cannot be applied. As N-acyl amino acids lacking a third substituent at nitrogen failed to undergo ring-closure, several N-protecting groups were evaluated. With the use of the removable PMB-group, an N-unsubstituted 1,4-oxazepane-2,5-dione
已知几种含有1,4-氧杂庚烷-2,5-二酮核的天然产物。一个例子是从粘质沙雷氏菌中分离出的塞拉汀。由于存在优先选择反式构象的羧酸酰胺,并且在该核心中存在不稳定的内酯,因此无法应用许多通常用于环化成中型杂环的合成方法。作为N-酰基氨基酸缺乏在氮气的第三取代基没有经历闭环,几个ñ -保护基团进行了评价。通过使用可移除的PMB基团的,一个N -合成未取代的1,4-氧杂庚烷-2,5-二酮。通过应用假脯氨酸(即,丝氨酸衍生的恶唑烷作为另一种保护基),获得具有天然产物塞拉汀的推测结构的化合物。由于光谱数据的差异,发现了天然产物塞拉汀的结构不正确。代替了预测的七元杂环,有人提出了一种对称的Serratamolide类似物是塞拉汀的正确结构。