Tsitopoulou Maria, Clemenceau Antonin, Thesmar Pierre, Baudoin Olivier
Department of Chemistry, University of Basel, CH-4056 Basel, Switzerland.
J Am Chem Soc. 2024 Jul 17;146(28):18811-18816. doi: 10.1021/jacs.4c04701. Epub 2024 Jul 5.
1,4-Palladium migration has been widely used for the functionalization of remote C-H bonds. However, this mechanism has been limited to aryl halide precursors. This work reports an unprecedented Pd-catalyzed cyclobutanation protocol producing valuable fused cyclobutanes starting from cycloalkenyl (pseudo)halides. This reaction takes place via alkenyl-to-alkyl 1,4-Pd migration, followed by intramolecular Heck coupling. The method performs best with cyclohexenyl precursors, giving access to a variety of substituted bicyclo[4,2,0]octenes. Reactants containing an -methyl or methoxy group give rise to fused azetidines or oxetanes, respectively, via the same mechanism. Kinetic and deuterium-labeling studies point to a rate-limiting C(sp)-H activation step.
1,4-钯迁移已被广泛用于远程碳氢键的官能团化。然而，这种机理仅限于芳基卤化物前体。本文报道了一种前所未有的钯催化环丁烷化反应，该反应从环烯基（伪）卤化物开始，生成有价值的稠合环丁烷。该反应通过烯基到烷基的1,4-钯迁移，随后进行分子内Heck偶联来进行。该方法对环己烯基前体效果最佳，可得到各种取代的双环[4,2,0]辛烯。含有α-甲基或甲氧基的反应物分别通过相同的机理生成稠合氮杂环丁烷或氧杂环丁烷。动力学和氘标记研究表明，碳（sp）-氢键活化步骤是速率决定步骤。
