Allenylidene Induced 1,2‐Metalate Rearrangement of Indole‐Boronates: Diastereoselective Access to Highly Substituted Indolines
作者:Amit Kumar Simlandy、M. Kevin Brown
DOI:10.1002/anie.202103108
日期:2021.5.25
A process to achieve 1,2‐metalate rearrangements of indole boronate as a way to access substitutedindolines in high diastereoselectivities is presented. The reaction involves the generation of a Cu–allenylidene, which is sufficiently electrophilic to induce the 1,2‐metalate rearrangement. The scope of the reaction is evaluated as well as further transformations of the product.
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.
The first nickel-catalyzed aromatic C–H borylation is described. In the presence of catalytic amounts of [Ni(cod)2], tricyclopentylphosphine, and CsF, benzene and indole derivatives can be borylated with B2pin2. The N-heterocyclic carbene IPr was also found to be an effective ligand. Kinetic isotope effect experiments showed that C–H cleavage is likely involved in the rate-determining step.
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.