Palladium-Catalyzed Non-Directed C─H Functionalization of Arenes with Trifluoromethylated Olefins

Abstract

Herein, we report the palladium-catalyzed non-directed C─H functionalization reaction of simple arenes with α-trifluoromethyl styrene derivatives. The application of 2-pyridone ligands increased the yield and selectivity of the alkenylation reaction and enabled a broad scope of different simple arenes and α-trifluoromethyl styrenes (25 examples, up to 94% yield). Overall, a robust reaction is developed as described by a sensitivity screening. Detailed experimental studies on the reaction were performed to further understand the mechanism. Palladium-catalyzed non-directed C─H alkenylation of simple arenes with α-trifluoromethyl styrene derivatives is accomplished using 2-pyridone ligands, which significantly enhances both yield and selectivity. This approach enables efficient functionalization across a wide range of arenes and styrene substrates. Mechanistic studies further clarify the reaction pathway.

Keywords: C─H Functionalization; Pd‐catalysis; fluorine chemistry; trifluoro methylated olefines.

Scheme 1

A From classic Fujiwara‐Moritani conditions toward non‐directed C─H activation; B α‐trifluoromethyl styrene derivatives as reaction partner; C Classic cross‐coupling reactions for the synthesis of 3,3,3‐trifluoroprop‐1‐ene‐1,2‐diyl)dibenzene; D Non‐directed C─H activation with α‐trifluoromethyl styrene derivatives.

Scheme 2

A Influence of 2‐pyridon ligands on the selectivity; B sensitivity screening.

Scheme 3

Scope of different arenes in non‐directed C─H functionalization reaction with α‐trifluoromethyl styrene derivatives yields refer to isolated E‐isomers.

Scheme 4

A Investigation of reaction kinetics of different α‐trifluoromethyl styrene derivatives; B Investigation of kinetic isotope effect; C Proposed catalytic cycle. Combined yields of E‐ and Z‐product are presented .