Anodic oxidation of compounds having benzylic or allylic carbon and .ALPHA.-carbon to hetero atom using N-hydroxyphthalimide as a mediator.

Co/NHPI-mediated aerobic oxygenation of benzylic C–H bonds in pharmaceutically relevant molecules

“…20,21 These methods generate PINO via electrochemical oxidation of NHPI ( i.e. , in the absence of cobalt ions) and, therefore, should not be susceptible to chelate-inhibition by the product.…”

Reactivity of phthalimide-N-oxyl : A kinetic study.

“…Many sorts of compounds including alcohols,1) those having a benzylic carbon or a-carbon to a hetero atom,2) olefins,3) amides and lactams,4) ketals,5) and aldehyde acetals6) were found to be substrates for the mediation. The reaction mechanism has been considered to be as shown in Chart 1, in which the phthalimide-N-oxyl radical (2) Third, higher reactivity of five-membered-ring substrates compared to the corresponding six-membered ones, except for the case of cycloalkene, is also suggested. These results account for the poor efficiencies of the six-membered substrates in the mediating system.…”

“…Tetrahydrothiopyfan and N-benzoylpiperidine gave the oxidation products in only 8 and 9% yields, respectively,19) while the corresponding five-membered analogs gave the products in 30 and 79% yields, respectively.2,4) Furthermore, tetrahydropyran was practically not oxidizable in the system but tetrahydrofuran gave the lactone in 11% yields. 2) Although quantitative treatment of the structure-reactivity relationship of the substrate toward2 was not successful, the chemical characterization of the reaction has been achieved. Advantages of 2 as a reagent for the hydrogen abstraction reaction have also been revealed.…”

A Partial Synthesis of the Skeleton of Deoxypumiloside, a Putative Intermediate in Camptothecin Biosynthesis

“…The enol ether 7 was assumed to be the required substrate to direct tertiary amine oxidation towards the C-21 position, due to its allylic character (biogenetic numbering for camptothecin and heteroyohimbane derivatives). [9] Allylic tertiary amines have been oxidized to amides by a few methods including electrochemical anodic oxidation [10] and the use of chromium trioxideϪpyridine complex, [11] manganese dioxide, [12] ozone, [13] and potassium permanganate. [14] Furthermore, two sets of oxidation conditions Ϫ Hg(OAc) 2 /EDTA·4Na (pH ϭ 8) [15] and I 2 /NaHCO 3 [16] Ϫ are known to be compatible with an unprotected indole group.…”