MN(III)-MEDIATED IN-CELL ELECTROCHEMICAL ADDITION OF ACTIVE METHYLENE-COMPOUNDS TO OLEFINS - SYNTHETIC AND MECHANISTIC ASPECTS

The Mn-mediated in-cell electrochemical addition of active methylene c ompounds is an interesting alternative to usual chemical methods notab ly with respect to the amount of manganese salt used. The electrochemi cal approach however requires the reagent to be readily oxidized in or der to be associated with an efficient in situ, anodic regeneration pr ocess. We have used amperometric measurements to show that the rate co nstants for the Mn(III)-oxidation of active methylene compounds at 60 degrees C range between 10(-2) and 1.2 L mol(-1) s(-1). In this study we show that the addition reaction occurs in the coordination sphere o f Mn; this requires the active methylene compound and the olefin to be coordinated to the Mn salt. This aspect can be critical in the electr ochemical process insofar as the catalytic manganese salt can sometime s be fully coordinated by only one reagent, either the active methylen e compound (eg, 2,4-pentanedione) or the olefin (eg, styrene).