Wang Qiang, An Jing, Alper Howard, Xiao Wen-Jing, Beauchemin André M
CCNU-uOttawa Joint Research Centre, Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, 152 Luoyu Road, Wuhan, Hubei 430079, China.
Chem Commun (Camb). 2017 Dec 5;53(97):13055-13058. doi: 10.1039/c7cc07926e.
O-Substituted isocyanates (O-isocyanates) have rarely been used in organic synthesis, given their tendency to undergo side reactions (e.g., trimerization). Herein, we show that masked (blocked) O-isocyanate precursors allow one-pot or cascade reaction sequences featuring base-catalyzed substitution with 2-iodoanilines and 2-iodobenzylamines followed by copper-catalyzed cyclization, to form benzimidazolones and 3,4-dihydroquinazolin-2(1H)-ones. This work shows that O-isocyanates can serve as efficient building blocks for the synthesis of hydroxylamine-containing heterocycles.
O-取代异氰酸酯（O-异氰酸酯）由于倾向于发生副反应（如三聚反应），在有机合成中很少被使用。在此，我们表明，掩蔽（受阻）的O-异氰酸酯前体能够实现一锅法或串联反应序列，其特征在于通过碱催化与2-碘苯胺和2-碘苄胺进行取代反应，随后进行铜催化环化反应，以形成苯并咪唑酮和3,4-二氢喹唑啉-2(1H)-酮。这项工作表明，O-异氰酸酯可作为合成含羟胺杂环的有效结构单元。
