TRANSFER REACTIONS INVOLVING BORON .19. OXIDATION STUDIES INVOLVING MONO- AND BISBORONIC ACID DERIVATIVES OF PHENYLETHYL AND STYRYL SYSTEMS

The oxidation of the 1- and 2-phenylethaneboronic esters (4 and 1), α- and β-styreneboronic esters (5 and 2), 2-phenylethane-1,1-bisboronic ester (3), and 1-phenylethane-1,2-bisboronic ester (6) with basic hydrogen peroxide and Fenton's reagent has been extensively studied. Compounds 1, 2, 4 and 5 undergo normal oxidations with basic hydrogen peroxide to give the expected alcohols and carbonyl compounds. Similar treatment of 3 gives a number of products of which the CC bond cleavage products benzaldehyde and benzyl alcohol predominate (up to 60% and 20% respectively). Basic hydrogen peroxide oxidation of 6 similarly produces a number of products including benzaldehyde and acetophenone. Compounds 2, 3, 4 and 6 react with Fenton's reagent to produce a number of products including CC bond cleavage and elimination products. Mechanisms are proposed for these oxidation reactions based on the known radical reactivity of compounds 1, 3, 4 and 6, the known chemistry involving Fenton's reagent, and oxidation studies of selected model systems with Fenton's reagent. The following important conclusions may be drawn from this study: (1) Reactions with basic solutions of hydrogen peroxide may produce radical reactions involving hydroxyl and/or hydroperoxyl radical; (2) Reactions with Fenton's reagent involve both hydroxyl and hydroperoxyl radicals (the latter believed to be predominating) in addition reactions with olefins and radical combination reactions. © 1969.