Successful Application of Indirect Electrooxidation for the Transformation of Biaryl Methanols to the Corresponding Biaryl Ketones

Abstract

Various biaryl methanols were electrooxidized into the corresponding biaryl ketones in good yields and under very mild reaction conditions. Because of the relatively high oxidation potential, bulky structure, and somewhat poor solubility, biaryl methanols do not readily undergo direct electrooxidative transformations as a synthetic step toward the corresponding biaryl ketones. Herein, we report the successful indirect electrooxidation of secondary biaryl methanols featuring the use of a slight excess amount of KI (1.2 equivalents, relative to the substrate) in MeOH.

Keywords:

• Biaryl ketones
• biaryl methanols
• electron transfer
• iodine ion
• oxidation

ACKNOWLEDGMENT

We are thankful for the financial support of the President's Discretionary Finance Council of Kitami Institute of Technology (2008–2009).

Notes

^a 1a, 5 mmol; MeOH, 40 mL; constant current, 0.3 A; current passed, 13.4 Fmol⁻¹; rt ca. 20 °C.

^b Yields were determined by GC analysis.

^a 1, 5 mmol; KI, 6 mmol; NaOMe, 10 mmol; MeOH, 40 mL; constant current, 0.3 A; rt ca. 20 °C.

^b Isolated yields based on the substrates.