Markovnikov-Selective Hydroboration of Aryl Alkenes Catalyzed by Quaternary Ammonium Salts

The
development of catalytic Markovnikov-selective hydroboration
of alkenes has seen significant progress; however, achieving this
transformation under metal-free conditions has remained a longstanding
challenge. Here, we present an organocatalytic method for the Markovnikov-selective
hydroboration of aryl alkenes using a readily available quaternary
ammonium catalyst. This approach is operationally simple, scalable,
and demonstrates broad substrate compatibility. Furthermore, the method
enables the efficient synthesis of active pharmaceutical ingredients,
including Chlorphenoxamine. Comprehensive experimental and computational
studies provide detailed insights into the reaction mechanism and
the origins of its regioselectivity, offering a deeper understanding
of this transformation.