RHAT-Enabled Deoxyfunctionalization of Cyclic Acetals Derived from Vicinal Diols.

Area of Science:

• Organic Chemistry
• Synthetic Chemistry

Background:

• Selective activation of strong carbon-oxygen (C-O) bonds in diols is challenging due to high bond energies.
• Existing methods for diol functionalization often lack regioselectivity or require harsh conditions.

Purpose of the Study:

• To develop a regioselective radical deoxygenative strategy for functionalizing cyclic acetals derived from vicinal diols.
• To synthesize deconjugated alkenes under mild, visible-light-driven conditions.

Main Methods:

• Utilized a visible-light-driven radical deoxygenative approach.
• Employed cyclic acetals derived from vicinal diols and various alkynes as substrates.
• Conducted mechanistic studies including radical trapping, isotopic labeling, and density functional theory (DFT) calculations.

Main Results:

• Achieved regioselective synthesis of deconjugated alkenes from six-membered and larger cyclic acetals.
• Demonstrated broad substrate scope for both cyclic acetals and alkynes.
• Obtained moderate to excellent yields and high regioselectivity in product formation.

Conclusions:

• Established a novel platform for site-selective functionalization of vicinal diols.
• Highlighted the potential of regioselective hydrogen atom transfer (RHAT)-enabled strategies for C-O bond activation.
• The proposed mechanism involves a sequential RHAT/radical addition/RHAT/C-O cleavage pathway.