Catalytic Direct Cyanomethylenation of C(sp3)–H Bonds via a One-Step Double C–C Bond Formation

An elegant and catalytic procedure for the one-step cyanomethylenation of C­(sp3)–H bonds adjacent to benzazoles and ketones is described herein using DMF as a C-1 unit and TMSCN as the cyanide source. The copper-mediated reaction between DMF and TMSCN gives a cyanomethylene radical intermediate that reacts with 2-alkylbenzazoles or alkylketones to furnish desired cyanomethylenated compounds under palladium catalysis. Subsequent interconversion of cyanomethylenated products makes the protocol synthetically attractive.本文报道了一种精巧高效的催化合成方法，以N,N-二甲基甲酰胺(DMF)作为C1合成子、三甲基硅基氰(TMSCN)作为氰源，实现了苯并唑类(benzazoles)与酮类(ketones)邻位碳(sp3)-氢键的一步氰基亚甲基化反应。铜介导的DMF与TMSCN反应首先生成氰基亚甲基自由基中间体，该中间体可在钯催化下与2-烷基苯并唑或烷基酮反应，从而得到目标氰基亚甲基化产物。后续可对所得氰基亚甲基化产物进行衍生转化，使得该合成策略具备优异的合成应用价值。