Azopeptides: Synthesis and Pericyclic Chemistry

Azopeptides possess an imino urea as an amino amide surrogate in the sequence. Azopeptides were synthesized by oxidation of aza-glycine residues and employed in pericyclic chemistry. Diels–Alder cyclizations and Alder–ene reactions on azopeptides enabled construction of constrained aza-pipecolyl and reactive aza-allylglycyl residues. X-ray crystallographic analyses of azopeptide 16a and azapeptides 30a and 35a provided insight into imino urea configuration and conformational affects of cycloalkane side chains at the semicarbazide α- and β-nitrogen, respectively.氮杂肽（azopeptides）在其序列中以亚氨基脲作为氨基酰胺替代基。该类化合物通过氮杂甘氨酸（aza-glycine）残基的氧化反应合成，并被应用于周环反应化学研究。针对氮杂肽开展的狄尔斯-阿尔德（Diels–Alder）环化反应与阿尔德-烯（Alder–ene）反应，可用于构建受限氮杂哌啶酰基与活性氮杂烯丙基甘氨酰基残基。对氮杂肽16a、30a及35a进行的X射线晶体结构分析，为解析亚氨基脲构型以及氨基脲（semicarbazide）α位与β位氮原子上环烷烃侧链的构象影响提供了关键依据。