Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
J Am Chem Soc. 2012 Sep 12;134(36):14662-5. doi: 10.1021/ja306037w. Epub 2012 Aug 27.
Under H(2), the radical cyclization of appropriate dienes can be catalyzed by cobaloximes. H• can be abstracted from an intermediate (presumably a cobalt hydride) by trityl radicals (Ar(3)C•) or by TEMPO. The rate-determining step in these reactions is the uptake of H(2), which is second order in cobalt and first order in hydrogen; the third-order rate constant is 106(3) M(-2)·s(-1).
在 H(2)下,合适的二烯可以通过钴卟啉催化进行自由基环化。H•可以通过三苯甲基自由基(Ar(3)C•)或 TEMPO 从中间产物(推测为钴氢化物)中提取。这些反应的速率决定步骤是 H(2)的吸收,它在钴中为二级,在氢中为一级;第三级速率常数为 106(3) M(-2)·s(-1)。