Anodic Cleavage of Several Ketone N-Phenylsemicarbazones into Methyl N-Phenylcarbamate and the Corresponding Dimethyl Acetals

Abstract

Several ketone N-phenylsemicarbazones were electrooxidized in the presence of potassium iodide and a base using methanol as the solvent to give nearly commensurate amounts of methyl N-phenylcarbamate and the corresponding dimethyl acetals. Continuous evolution of gaseous nitrogen was observed from the anolyte during the electrooxidation. The reactions were carried out under very mild reaction conditions and are presumed to proceed through a four-electron oxidation process, in which the iodide ion plays an important role as an electron carrier.

GRAPHICAL ABSTRACT

Keywords:

• Dimethyl acetal
• electron carrier
• electrooxidation
• iodonium ion
• ketone N-phenylsemicarbazone
• methyl N-phenylcarbamate

Notes

^a 1f (2.03 g, 8 mmol), MeOH (40 mL), constant current: 0.3 A, current passed: 4.2 Fmol⁻¹, rt (ca. 20 °C).

^b Yields were determined by GC analysis using the internal standard (phenyl ether) method.

^a 1 (8 mmol), KI (7.5 mmol), NaOMe (2.5 mmol), MeOH (40 mL), constant current: 0.3 A, rt (ca. 20 °C).

^b Determined by GC analysis using the internal standard method.

^c Electrolysis was carried out in the absence of any base.

^d t-BuOH (20 mL) was used as a cosolvent. The amount of NaOMe was increased to 5.0 mmol.