Iridium-Catalyzed Distal Hydroboration of Aliphatic Internal Alkenes

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Regioselective hydroboration of internal alkenes is a persistent challenge in organic synthesis.
• Developing efficient catalytic systems for direct functionalization of C-H bonds is crucial.

Purpose of the Study:

• To develop a novel iridium-catalyzed method for the regioselective hydroboration of aliphatic internal alkenes.
• To explore the synthetic utility of the resulting distal-borylated products.
• To elucidate the catalytic cycle mechanism.

Main Methods:

• Iridium-catalyzed hydroboration reaction using various aliphatic internal alkenes.
• Characterization of products using NMR spectroscopy and mass spectrometry.
• Density Functional Theory (DFT) calculations to investigate the reaction mechanism.

Main Results:

• Achieved high yields (good to excellent) and excellent regioselectivity (up to 99:1) in the hydroboration of aliphatic internal alkenes.
• Demonstrated the facile conversion of the carbon-boron bond into other functional groups.
• DFT calculations suggested an unprecedented Ir^III/Ir^V catalytic cycle.

Conclusions:

• The developed iridium-catalyzed hydroboration provides an effective solution for the regioselective synthesis of distal-borylated alkanes.
• The methodology offers a versatile platform for further functionalization, expanding its synthetic applicability.
• The proposed Ir^III/Ir^V cycle provides mechanistic insight into this challenging transformation.