# Boron-Mediated Hydroalkylation of Unactivated Olefins: An Anti-Markovnikov Approach to Congested Carbon Centers

## TL;DR

A new chemical method enables the creation of complex carbon structures using boron and nickel/photoredox catalysis.

## Contribution

A boron-mediated coupling strategy enables anti-Markovnikov hydroalkylations of unactivated olefins with carboxylic acid derivatives.

## Key findings

- The method allows the formation of sterically congested quaternary carbon centers.
- The process involves hydroboration followed by radical generation and substitution.
- This approach provides a solution to a longstanding challenge in fragment-coupling chemistry.

## Abstract

Transition metal-catalyzed hydroalkylations offer efficient
routes
to install alkyl fragments onto readily available olefins. However,
the formation of quaternary carbon centers through olefin hydroalkylations
with tertiary alkyl electrophiles remains a formidable synthetic challenge.
Difficulty arises as a result of steric congestion, which slows the
rate of oxidative addition and promotes deleterious β-hydride
elimination. Here, we report a boron-mediated coupling strategy using
nickel/photoredox dual catalysis that circumvents these limitations
and enables anti-Markovnikov hydroalkylations of
unactivated olefins with carboxylic acid derivatives as alkylating
partners. Our protocol proceeds via initial hydroboration, followed
by a sequence of deboronative and decarboxylative radical generation,
radical sorting, and bimolecular homolytic substitution (SH2). This mild and practical approach allows the construction of densely
substituted carbon frameworks, including sterically congested quaternary
carbon centers, providing a solution to a long-standing challenge
in fragment-coupling chemistry.