# Inverse‐Electron‐Demand Diels–Alder Reaction of Tropone with Graphene Supported on Cu(111)

## TL;DR

Researchers used a chemical reaction to modify graphene on a copper surface, showing how different catalysts lead to different structures and how graphene curvature affects the reaction.

## Contribution

The study introduces a new strategy for graphene functionalization using inverse-electron-demand Diels–Alder reactions with catalyst-dependent selectivity.

## Key findings

- B(C6F5)3 catalysis leads to [4 + 2] cycloaddition with carbonyl group formation.
- BPh3 catalysis results in [8 + 2] cycloaddition with C─O group formation.
- Curved graphene and substrate interactions enhance reaction favorability.

## Abstract

An inverse‐electron‐demand Diels–Alder (IEDDA) reaction between graphene supported on Cu(111) and tropone catalyzed by a Lewis acid is reported. Reaction catalyzed by B(C6F5)3 resulted in a significant change in the Raman G band and the appearance of carbonyl group in the functionalized graphene. Treating the product with a reducing agent NaBH4 or hydrazine led to a near complete disappearance of shoulder peaks in the Raman G band and a decrease in carbonyl intensity. On the other hand, reaction catalyzed by BPh3 resulted in the appearance of C─O group in the functionalized graphene. The findings support [4 + 2] and [8 + 2] cycloaddition for the B(C6F5)3‐ and BPh3‐catalyzed reaction, respectively. Density functional theory (DFT) calculations revealed that favorable cycloaddition reactions with tropone can be achieved through the usage of curved graphene. The origin of the Lewis acid‐dependent selectivity inversion is predicted to be based on the requirement for Lewis acid dissociation during the course of the [8 + 2] reaction with B(C6F5)3 dissociation requiring more energy than BPh3 dissociation. This study represents a new strategy in graphene chemistry that combines synergistic activation of graphene via substrate interactions and of tropone via Lewis acid coordination, as well as catalyst selection to modulate reaction pathways.

The inverse‐electron‐demand Diels–Alder reaction between tropone and graphene supported on Cu(111), catalyzed by B(C6F5)3 or BPh3, gave [4 + 2] and [8 + 2] cycloadducts, respectively. Computations reveal that the cycloadditions become favorable on curved graphene with secondary substrate charge transfer effects and reveal the origins of the product selectivity reversal to be based on product Lewis acid coordination strength.