Cyclic Diaryl λ³ -Bromanes as Original Aryne Precursors

Area of Science:

• Organic Chemistry
• Hypervalent Iodine and Bromine Chemistry
• Synthetic Methodology

Background:

• Hypervalent iodine compounds are widely utilized in organic synthesis.
• Corresponding hypervalent bromine compounds (λ³-bromanes) remain significantly less explored.
• A gap exists in the synthetic utility of hypervalent bromine reagents compared to iodine counterparts.

Purpose of the Study:

• To develop a general, safe, and high-yielding synthetic strategy for cyclic diaryl λ³-bromanes.
• To explore the reactivity of these novel λ³-bromanes.
• To establish their utility in transition-metal-free coupling reactions.

Main Methods:

• Development of a novel synthetic route to cyclic diaryl λ³-bromanes.
• Investigation of the reactivity of λ³-bromanes under mild reaction conditions.
• Utilizing a weak base for aryne generation.
• Performing mechanistic studies to elucidate the reaction pathway.

Main Results:

• Successful synthesis of cyclic diaryl λ³-bromanes via a general, safe, and high-yielding method.
• Demonstration that these λ³-bromanes generate arynes under mild conditions with a weak base.
• Achieved meta-selective, transition-metal-free C-O and C-N couplings.
• Mechanistic studies confirmed the aryne generation pathway.

Conclusions:

• A robust strategy for accessing cyclic diaryl λ³-bromanes has been established.
• These compounds offer complementary reactivity to λ³-iodanes, particularly in aryne generation.
• The developed methodology enables efficient and selective metal-free C-O and C-N bond formations.