Electrooxidative Cleavage of Carbon-Carbon Linkages. 1. Preparation of Acylic Oxoalkanoates from 2-Hydroxy- and 2-Acetoxy-1-cycloalkanones and Cycloalkanone Enol Acetates

Article abstract of DOI:10.1021/jo00340a009

A methodology is described for the synthesis of acyclic oxoalkanoates 2 by electrooxidative cleavage of carbon-carbon linkages of 2-oxocycloalkan-1-ols 1 and cycloalkanone enol acetates 3.The electrolysis of 1 was carried out in a MeOH-LiClO4-(Pt) system at a constant applied voltage of 20 V by using a divided cell, giving 2 in 82-97 percent yields.On the other hand, 3 was electrolyzed in MeOH-AcOH (10:1)-LiClO4-(Pt) at 2-8 deg to give 2 in 72-79 percent yields.Electrolysis of 4-hydroxy-p-menth-8-ene afforded methyl (3R)-3,7-dimethyl-6-oxo-7-octenoate, a chiral synthetic block for the synthesis of (+)-rose oxide, in 84 percent yield.Similarly, the procedure could be applied to the preparation of methyl(+)-6-oxo-6,7-dihydrocitronellate from (+)-menthone enol acetate (74 percent) as well as 4-hydroxy-p-menthone (94 percent).Other lithium salts, i.e., LiBF4 and CF3CO2Li, can be used for the present purpose, but there are some difficulties in producing 2 with Et4NOTs and Et4NClO4.A plausible mechanism of the formation of 2 from 1 is also discussed.