Borenium-Catalyzed "Boron Walking" for Remote Site-Selective Hydroboration

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Remote functionalization offers synthetic versatility but often relies on transition metal catalysts.
• Transition metal catalysts present challenges like metal residue and catalyst poisoning.

Purpose of the Study:

• To develop a metal-free catalytic system for site-selective remote borylation.
• To establish a novel synthetic strategy that avoids transition metals for remote functionalization.

Main Methods:

• Utilized a borenium ion as a catalyst for remote borylation.
• Investigated reaction mechanisms through detailed mechanistic studies and DFT calculations.
• Explored the synthesis of silyl-remote-boryl compounds.

Main Results:

• Achieved site-selective remote borylation without transition metals.
• Demonstrated a stepwise migration of the boron moiety, converging to an alpha-borylation product.
• Showcased good functional group compatibility and opposite regioselectivity in silylation-borylation compared to metal-catalyzed reactions.

Conclusions:

• Pioneered a metal-free borenium ion-catalyzed protocol for remote borylation.
• Established a new pathway for site-selective remote difunctionalization via sequential C-B and C-Si bond formation.
• Provided a valuable alternative to transition metal-catalyzed methods for synthesizing complex organic molecules.