Catalytic substitution/cyclization sequences of <i>O</i>-substituted Isocyanates: synthesis of 1-alkoxybenzimidazolones and 1-alkoxy-3,4-dihydroquinazolin-2(1<i>H</i>)-ones
作者:Qiang Wang、Jing An、Howard Alper、Wen-Jing Xiao、André M. Beauchemin
DOI:10.1039/c7cc07926e
日期:——
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
考虑到O-取代的异氰酸酯(O-异氰酸酯)易于发生副反应(例如三聚)的趋势,因此很少用于有机合成中。在这里,我们表明,被掩盖的(封闭的)O-异氰酸酯前体允许一锅或级联反应序列,其特征在于用2-碘苯胺和2-碘苄胺进行碱催化的取代,然后进行铜催化的环化反应,形成苯并咪唑酮和3,4-二氢喹唑啉-2(1 H)-ones。这项工作表明,O-异氰酸酯可以作为合成含羟胺杂环的有效构件。