Chang Yu-Hsiang, Shen Weijia, Shezaf Jonathan Z, Ortiz Eliezer, Krische Michael J
Department of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States.
J Am Chem Soc. 2023 Oct 25;145(42):22890-22895. doi: 10.1021/jacs.3c09876. Epub 2023 Oct 16.
The first deoxygenative Heck reactions are described, as illustrated by formate-mediated -substitutions of vinyl triflates with aryl iodides. The collective data corroborate a mechanism in which Pd(OAc) and BuNI form the dianionic iodide-bridged dimer [PdI][NBu], which, under reducing conditions, serves as a precursor to the palladium(I) complex [PdI][NBu]. Dinculear oxidative addition of aryl iodide forms [PdI(Ar)][NBu], which dissociates to the monometallic complex [PdI(Ar)][NBu]. Vinyl triflate migratory insertion-sulfonate elimination delivers a palladium(IV) carbene, which upon β-hydride elimination/C-H reductive elimination gives the product of -substitution. These processes are the first efficient formate-mediated cross-electrophile reductive couplings beyond carbonyl addition.
首次描述了脱氧Heck反应，以甲酸盐介导的乙烯基三氟甲磺酸酯与芳基碘的β-取代为例进行说明。综合数据证实了一种机制，即Pd(OAc)和BuNI形成双阴离子碘桥联二聚体[PdI][NBu]，在还原条件下，它作为钯(I)配合物[PdI][NBu]的前体。芳基碘的双核氧化加成形成[PdI(Ar)][NBu]，其分解为单金属配合物[PdI(Ar)][NBu]。乙烯基三氟甲磺酸酯的迁移插入-磺酸酯消除产生钯(IV)卡宾，经β-氢消除/C-H还原消除后得到β-取代产物。这些过程是首次在羰基加成之外实现的高效甲酸盐介导的交叉亲电还原偶联反应。
