# Pd-catalyzed regiodivergent arylation of cyclic allylboronates

## TL;DR

This paper presents two different palladium-catalyzed reactions that selectively attach aryl groups to cyclic allylboronates, offering new methods for organic synthesis.

## Contribution

The study introduces two regiodivergent Pd-catalyzed arylation methods with distinct selectivity using different ligands.

## Key findings

- Using a (P,N) ligand leads to highly C1-selective arylation.
- A Buchwald-type monophosphine ligand results in highly C3-selective arylation.
- DFT calculations reveal a solvated dimer of the substrate is involved in the reaction mechanism.

## Abstract

Two complementary regiodivergent Pd-catalyzed arylations of the lithium salts of 6-membered cyclic allylboronates are reported. The two systems provide access to products featuring a polysubstituted alkene and a boronic ester and are both compatible with a broad range of aryl bromides or heteroaryl bromides. When a (P,N) ligand is employed, a highly C1-selective arylation is favored. With the use of a Buchwald-type monophosphine ligand, a highly C3-selective arylation is favored. DFT calculations served to establish that a solvated dimer of the substrate is involved rather than a monomeric allylboronate. For the C3-arylation pathway, regioselectivity is governed mostly by steric factors during binding of the substrate to the metal center. A Curtin–Hammett equilibrium is crucial in determining C1 selectivity for the second catalytic system. A pivotal isomerization between two η2-alkene-Pd(ii) intermediates precedes ring-opening transition states and irreversible reductive elimination.

Two complementary regiodivergent Pd-catalyzed arylations of the lithium salts of 6-membered cyclic allylboronates are reported.