Electroorganic synthesis. 1. Electrode-catalyzed synthesis of a dioxetane

Abstract

Successful synthesis of a 1,2-dioxetane was not accomplished until 1968 when the synthesis of trimethyl-1,2-dioxetane was reported.1 Since that time many 1,2-dioxetanes have been synthesized and characterized.2 Four synthetic methods have been utilized in their production: (1) closure of a /3-halohydroperoxide with base, (2) addition of singlet oxygen to enol ethers, enamines, and alkenes with unreactive allylic hydrogens, (3) assisted closure of a /3-halohydroperoxide with silver ion, and (4) 9,10-dicyanoanthracene (DCA) photooxidations.3We now report a fifth method which we have used for the synthesis of adamantylideneadamantane dioxetane. A solution consisting of 50 mL of methylene chloride, 1.71 g of tetra-n-butyl ammonium perchlorate, and 104.5 mg of adamantylideneadamantane (1) was subjected to a constant potential electrolysis (1.6 V vs. SCE) at a platinum gauze electrode. The electrolysis was conducted while the solution was continually agitated by bubbling oxygen vigorously through the cell and until current passage through the cell ceased. The methylene chloride was then

Electrochemical oxidation of silacyclopentadienes (siloles)

“…The electrochemical oxidation of silacyclopentadienes may take a different reaction pathway, involving an initial electron uptake to form a cationradical, followed by various consecutive chemical reactions. Thus, electrolysis under an air atmosphere could lead to a reaction between an electrochemically generated cation-radical of a silacyclopentadiene with molecular oxygen, in analogy to the chemical reactions found between oxygen and radical-cations of olefins [20,21] and dienes [22]. The possible involvement of molecular oxygen is supported by our previous observation that entirely different products were obtained when electrolysis of X was conducted under argon compared to air [16].…”

Electrochemical oxidation germacyclopentadienes (germoles)

“…The reaction between an electrochemically generated cation-radical of a germacyclopentadiene with molecular oxygen is not unusual because it resembles the chemical reactions found between molecular oxygen and radical-cations of olefins [37,38] and dienes [39]. Also, one cannot rule out other mechanisms for the formation of some of the products described in Scheme 2.…”

Photoinduced electron transfer oxygenations

“…In spite of this elegant demonstration, the intermediacy of these short-lived compounds required further direct evidence. In this regard, although different mechanistic pathways can account for the reaction products [34,120,121], Schaap et al [98] equatorial hydrogens [122], whereas, for structural necessity, the p-dioxin dioxetanes are planar [123]. On the contrary, the route to epoxides, which are minor products in the DCA-sensitized photooxygenation of aryl-olefins, in spite of the hypotheses of Foote et al, is still uncertain [95].…”

“…However, in the latter case, the fact that electron-transfer quenching reaction between the two species can generate singlet oxygen makes this reaction dificult to quantify [I13]. Moreover, 21 undergoes an easy electrode-catalyzed [121] and/or thermally induced oxygenation [120] through a chain radical cation electron-transfer process, in which the active oxygen species is the triplet molecular oxygen. As a consequence, with substrates whose radical cations are oxygen sensitive, it is not clear when the [2 + 2]-cycloaddition reaction goes by way of singlet oxygen, and/or electrontransfer (Foote-type) or Barton-type processes.…”