Department of Chemistry , North Carolina State University , Raleigh , North Carolina 27695-8204 , United States.
Org Lett. 2018 May 4;20(9):2564-2567. doi: 10.1021/acs.orglett.8b00713. Epub 2018 Apr 25.
Mild conditions for oxime ligations via in situ generation of α-imino amide intermediates are reported. The evaluation of a variety of N-terminal N-phenylglycine residues revealed that a metal-free, chemoselective oxidation was possible using oxygen as the only oxidant in buffer at pH 7.0. Moreover, selective unmasking of an inert residue by addition of potassium ferricyanide is demonstrated. These simple and mild conditions, which can be fine-tuned by the electronic properties of the N-phenylglycine residue, offer unique advantages over conventional approaches for oxime ligations.
报道了通过原位生成α-亚氨基酰胺中间体实现肟键连接的温和条件。对各种 N-端 N-苯甘氨酸残基的评估表明，在 pH 值为 7.0 的缓冲液中，仅使用氧气作为氧化剂，无需金属即可实现化学选择性氧化。此外，还证明了通过添加铁氰化钾可以选择性地掩蔽惰性残基。与传统肟键连接方法相比，这些简单温和的条件可通过 N-苯甘氨酸残基的电子性质进行微调，具有独特的优势。
