Diastereoselective anodic hetero- and homo-coupling of menthol-, 8-methylmenthol- and 8-phenylmenthol-2-alkylmalonates

• Matthias C. Letzel,
• Hans J. Schäfer and
• Roland Fröhlich

Beilstein J. Org. Chem. 2017, 13, 33–42, doi:10.3762/bjoc.13.5

• . Keywords: anodic decarboxylation; diastereoselectivity; Kolbe electrolysis; radical hetero-coupling; radical homo-coupling; Introduction Intermolecular radical additions with high diastereoselectivity have been described for a number of cases [1][2][3][4][5][6][7][8][9]. There are much fewer reports on

• coupling in high yield with good stereocontrol [38][39][40]. With the auxiliary controlled alkylation of enolates products being analogous to radical hetero-coupling can be synthesized [41][42]. However, both methods require costlier reaction conditions as inert gas, dry solvents and LDA as reagent, and

• interaction between the carbonyl and the phenyl group [24]. In order to enhance this interaction, the phenyl group was replaced for the more electron-rich anisyl group by applying 8-anisylmenthol (4) as chiral auxiliary. However, with acetic acid or 3,3-dimethylbutyric acid (20) as coacid no radical hetero