Strain-Release Induced 1,2-Metallate Rearrangement of Geminal Diborons: Multicomponent 1,5-Difunctionalization via...

Area of Science:

• Organic Chemistry
• Organometallic Chemistry
• Synthetic Methodology

Background:

• 1,2-metallate rearrangement of geminal diboryl alkanes typically leads to monofunctionalization.
• Existing methods often require an alpha-leaving group for proximal carbon functionalization.

Purpose of the Study:

• To develop a new strategy for 1,2-boronate shift using non-terminal geminal diborons.
• To achieve proximal and remote 1,5-difunctionalization via ring-opening of vinyl cyclopropyl diborons (VCPDBs).

Main Methods:

• Utilized strained vinyl cyclopropyl diborons (VCPDBs) in a multicomponent reaction.
• Employed an iridium-catalyzed allylation with a chiral ligand for potential enantioenrichment.
• Investigated reaction mechanisms using 11B NMR spectroscopy.

Main Results:

• Achieved 1,5-difunctionalization yielding homoallylic diboryl alkanes with allylic halide or branched 1,5-diene motifs.
• Demonstrated polarity inversion compared to previous cyclopropyl ring-opening reactions.
• Obtained alkenyl products with high E-stereoselectivity and showed downstream synthetic utility.

Conclusions:

• This work presents the first strain-release induced 1,2-metallate rearrangement on geminal diborons.
• Developed a novel Ir-catalyzed multicomponent allylation of organoborons beyond 1,2 or 1,3-addition.
• The VCPDB reaction offers a versatile route to densely functionalized molecules relevant to natural product synthesis.