Deoxygenative Functionalization of Unprotected Phenols by Linear Paired Electrolysis

Area of Science:

• Organic Chemistry
• Electrochemistry
• Sustainable Chemistry

Background:

• Phenols are abundant renewable feedstocks derived from lignin.
• Functionalizing inert phenolic C(sp2)─OH bonds is challenging, requiring harsh conditions or preactivation.
• Direct valorization of phenols is crucial for sustainable chemical synthesis.

Purpose of the Study:

• To develop a mild and sustainable electrochemical method for direct phenolic C(sp2)─OH bond cleavage.
• To enable hydrodeoxygenation and deoxygenative alkylation of phenols.
• To provide a general platform for phenol valorization without substrate preactivation.

Main Methods:

• Linear paired electrolysis was employed for direct C(sp2)─OH bond functionalization.
• The reaction utilized an amino phosphine and water under mild conditions.
• Mechanistic studies involved investigating in situ phosphinate intermediate formation and cathodic reduction.

Main Results:

• Successful direct hydrodeoxygenation and deoxygenative alkylation of phenols with alkenes were achieved.
• The method demonstrated compatibility with diverse functional groups and complex molecules, including natural and biomass-derived phenols.
• A key phosphinate intermediate was identified, crucial for the cathodic reduction process.

Conclusions:

• The developed electrochemical strategy offers a sustainable and direct approach for phenol valorization.
• This method avoids preactivation steps, simplifying the process for complex phenolic substrates.
• The findings open new avenues for utilizing renewable phenolic resources in organic synthesis.