Aryl Methyl Sulfides as Substrates for Rhodium-Catalyzed Alkyne Carbothiolation: Arene Functionalization with Activating Group Recycling

Abstract

A Rh(I)-catalyzed method for the efficient functionalization of arenes is reported. Aryl methyl sulfides are combined with terminal alkynes to deliver products of carbothiolation. The overall process results in reincorporation of the original arene functional group, a methyl sulfide, into the products as an alkenyl sulfide. The carbothiolation process can be combined with an initial Rh(I)-catalyzed alkene or alkyne hydroacylation reaction in three-component cascade sequences. The utility of the alkenyl sulfide products is also demonstrated in simple carbo- and heterocycle-forming processes. We also provide mechanistic evidence for the course of this new process.

Rh–POP Pincer Xantphos Complexes for C–S and C–H Activation. Implications for Carbothiolation Catalysis

“…Pentane, dichloromethane, benzene, and toluene were dried using a Grubbs type solvent purification system (MBraun SPS-800) and degassed by successive freeze−pump−thaw cycles. 52 (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(3,5-bis(trifluoromethyl)phenyl)phosphine, 56 2-(methylthio)-acetophenone, 20 4-(methylthio)acetophenone, 20 2-(2-(methylthio)-phenyl)-4,5-dihydrooxazole, 57 and 2-(2-(methylthio)phenyl)-pyridine 58 were prepared by literature methods. NMR spectra were recorded on a Bruker Avance III HD nanobay 400 MHz (Hg400) and Bruker DPX200 spectrometer at room temperature, unless otherwise stated.…”

Traceless Chelation‐Controlled Rhodium‐Catalyzed Intermolecular Alkene and Alkyne Hydroacylation

“…An inherent feature of chelation‐controlled reactions is that the chelating group, which is necessarily present in the starting materials to ensure favourable reactivity, is also present in the product molecules. Derivatization of these controlling groups can provide opportunities for further functionalization of the products,4d, 5a, 10 but if an unadorned molecule is required, they represent a limitation of the strategy. Although a number of examples of successful non‐chelation‐controlled intermolecular hydroacylation reactions is known, they generally require specific substrate combinations or harsh reaction conditions 11.…”

Activating Group Recycling in Action: A Rhodium-Catalyzed Carbothiolation Route to Substituted Isoquinolines

“…It also validates the utility of our recently reported “functional group recycling” approach to arene functionalization. 3 …”

“…3 Although complex A represents an efficient catalyst system, the use of the BAr F 4 counterion makes this catalyst relatively expensive and also difficult to prepare without the use of a glovebox. 9 …”