Manganese(I)‐Catalyzed C−H (2‐Indolyl)methylation: Expedient Access to Diheteroarylmethanes

Abstract

An unprecedented Mn -catalyzed (2-indolyl)methylation of heteroarenes is reported. This method makes use of an aromatizing cascade strategy to install a (2-indolyl)methyl group into target molecules, thereby leading to the expedient synthesis of previously challenging and important unsymmetrical diheteroarylmethanes, in particular bis(2-indolyl)methanes. The proposed cascade process comprises the reorganization of multiple bonds with controlled regioselectivity and high atom economy and can be performed on a gram-scale. Furthermore, a metal-free C-H propargylation is observed. The diverse application of this method is also demonstrated.

A comprehensive overview of directing groups applied in metal-catalysed C–H functionalisation chemistry

“…The use of 4-ethynyl benzoxazinanones, still under Mn catalysis, results in the C–H (2-indolyl)methylation of indoles and other heterocycles via alkyne insertion into the intermediate manganacycle, release of CO 2 , formation of an allene–Mn intermediate complex, and cyclisation with the nitrogen nucleophile ( Scheme 110M ). 667 Even in this case a robustness screening showed compatibility with a variety of FGs.…”

“…Recently, the Glorius group developed two important methods for the C–H propargylation and 2-(indolyl)methylation of indoles using substituted bromoallenes and 4-ethynyl benzoxazinanones ( Scheme 110L and M ). 666 , 667 Propargylation is a challenging transformation, as the corresponding allenylation might instead occur more easily. For this Mn-catalysed process, the use of BPh 3 as Lewis acid and a catalytic amount of H 2 O proved crucial for obtaining good yields and selectivity (with respect to the allene product).…”

Phosphine‐Free NNN‐Manganese Complex Catalyzed α‐Alkylation of Ketones with Primary Alcohols and Friedländer Quinoline Synthesis

“…Mainly, the current state‐of‐the‐art manganese catalysts established by the studies of Milstein, Beller,,, Kempe, Kirchner,, Sortais, Boncella and others utilizes diethylamine‐core PNP ligands, pyridinyl‐core PNP and PN 3 P ligands and triazinyl‐core PN 5 P ligands. However, the major concerns of these phosphine based pincer ligands in base‐metal catalysis are not only their cost, which are usually more expensive than the nonprecious metals by many folds, but also the difficulties lie in their preparations and handling under standard laboratory conditions.…”

Catalytic Transformations of Functionalized Cyclic Organic Carbonates

“…Based on the prior achievements made in this area, new opportunities upon using cyclic carbamates as substrates have been discovered. For example, Glorius and co‐workers discovered a regioselective aromatizing cascade strategy to introduce the (2‐indolyl)‐methyl motif onto heteroarenes through Mn I ‐catalyzed C−H activation employing ethynyl benzoxazinones (Scheme ) . The key to the success of this transformation is the use of a heteroaromatic substrate incorporating a 2‐pyridyl chelating group.…”