BF3⋅Et2O‐catalyzed C2‐selective C−H borylation of indoles with bis(pinacolato)diboron was developed to afford indole‐2‐boronicacid pinacol esters. A variety of functional groups were tolerated, and other heteroarenes like pyrrole and benzo[b]thiophene were also suitable substrates. An electrophilic substitution mechanism was proposed based on the preliminary mechanisticstudies. This novel transformation utilizes
Benzoic Acid-Promoted C2–H Borylation of Indoles with Pinacolborane
作者:Youliang Zou、Binfeng Zhang、Li Wang、Hua Zhang
DOI:10.1021/acs.orglett.1c00809
日期:2021.4.2
A benzoic acid-promoted C2–H borylation of indoles with pinacolborane to afford C2-borylated indoles is developed. Preliminary mechanistic studies indicate BH3-related borane species formed via the decomposition of pinacolborane to be the probable catalyst. This transformation provides a prompt route toward the synthesis of diverse C2-functionalized indoles.
Nickel-catalyzed borylation of arenes and indoles via C–H bond cleavage
作者:Takayuki Furukawa、Mamoru Tobisu、Naoto Chatani
DOI:10.1039/c5cc01378j
日期:——
The first nickel-catalyzed method for the borylation of carbon–hydrogen bonds in arenes and indoles is described. The use of an N-heterocyclic carbene ligand is essential for an efficient reaction, with an N-cyclohexyl-substituted derivative being optimal. This method is readily applied to the gram scale synthesis of 2-borylindole.
platinum-catalyzed borylation of aromatic C–H bonds. N-Heterocyclic carbene-ligated platinum catalysts are found to be efficient catalysts for the borylation of aromatic C(sp2)–H bonds when bis(pinacolato)diboron is used as the boron source. The most remarkable feature of these Pt catalysts is their lack of sensitivity towards the degree of steric hindrance around the C–H bonds undergoing the borylation reaction
Selective carbon–carbon bond activation is important in chemical industry and fundamental organic synthesis, but remains challenging. In this study, non-polar unstrained Csp2–Csp3 and Csp2–Csp2 bond activation was achieved by B(OMe)3/B2pin2-mediated fragmentation borylation. Various indole derivatives underwent C2-regioselective C–C bond activation to afford two C–B bonds under transition-metal-free