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
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.
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