Supporting-Electrolyte-Free Anodic Oxidation of Oxamic Acids into Isocyanates: An Expedient Way to Access Ureas, Carbamates, and Thiocarbamates
Supporting-Electrolyte-Free Anodic Oxidation of Oxamic Acids into Isocyanates: An Expedient Way to Access Ureas, Carbamates, and Thiocarbamates
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DOI：
10.1021/acs.oprd.1c00112
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发表时间：
2021-05
影响因子：
3.4
通讯作者：
Alessia Petti;Corentin Fagnan;Carlo G. W. van Melis;Nour Tanbouza;Anthony D. Garcia;Andrea Mastrodonato;M. Leech;I. Goodall;A. Dobbs;Thierry Ollevier;K. Lam
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作者：
Alessia Petti;Corentin Fagnan;Carlo G. W. van Melis;Nour Tanbouza;Anthony D. Garcia;Andrea Mastrodonato;M. Leech;I. Goodall;A. Dobbs;Thierry Ollevier;K. Lam
本文报道了一种新的无电解质支持下的草酸氧化合成脲、氨基甲酸酯和硫代氨基甲酸酯的方法。这种简单、实用且不含异氰酸酯的路线包括在有机碱存在下通过草氨酸的阳极脱羧原位生成异氰酸酯中间体，然后一锅加入合适的亲核试剂以提供相应的脲、氨基甲酸酯和硫代氨基甲酸酯。该程序适用于不同的胺、醇和硫醇。此外，当使用单程连续电化学流动条件并且该反应在碳石墨Cgr/Cgr流动池中进行时，可以在6分钟的停留时间内以高产率获得脲化合物，从而解锁对在间歇条件下不可接近的底物的接近，同时易于扩大规模。
We report a new electrochemical supporting-electrolyte-free method for synthesizing ureas, carbamates, and thiocarbamates via the oxidation of oxamic acids. This simple, practical, and phosgene-free route includes the generation of an isocyanate intermediate in situ via anodic decarboxylation of an oxamic acid in the presence of an organic base, followed by the one-pot addition of suitable nucleophiles to afford the corresponding ureas, carbamates, and thiocarbamates. This procedure is applicable to different amines, alcohols, and thiols. Furthermore, when single-pass continuous electrochemical flow conditions were used and this reaction was run in a carbon graphite Cgr/Cgrflow cell, urea compounds could be obtained in high yields within a residence time of 6 min, unlocking access to substrates that were inaccessible under batch conditions while being easily scalable.