OXIDATION OF DIETHYL (PYRIDYLMETHYL)MALONATES WITH MN(III) ACETATE, CE(IV) AMMONIUM-NITRATE, AND IRON(III) PERCHLORATE IN THE PRESENCE OF ALKENES AND ALKYNES

The oxidation of substituted diethyl 2-, 3-, or 4-picolylmalonates (1a-g) by Mn(III) acetate in acetic acid, Ce(IV) ammonium nitrate in methanol or acetic acid, and Fe(III) perchlorate in acetonitrile in the presence of substituted alkenes (2) and alkynes (3) affords substituted tetra- or dihydroquinolines and/or isoquinolines (4-9) in good to excellent yield. The influence of reaction medium on yield and isomer distribution has been investigated. A mechanism involving oxidative deprotonation of malonic esters by high-valent metal salts to malonyl radicals, their addition to olefins, and intramolecular homolytic substitution to protonated or metal-complexed heteroaromatic bases by the resulting substituted carbon radicals is suggested.