Synthesis of .alpha.-peroxylactones by direct oxygenation of ketenes. Evidence for an intermediate

Abstract

Sir:a-Peroxylactones possess inherent interest as high energy content molecules and importance as intermediates in chemiluminescent systems;' yet useful synthetic methods for pre-:t 17, I977 Sir: Since the first report by Murray et al.' on the success of chemically modifying a metal oxide electrode by covalently attaching reagents, other l a b o r a t o r i e~,~?~ have shown interest Journal of the American Chemical Society /

The reaction of singlet oxygen with olefins: the question of mechanism

“…The values do not rule out the possibility of a zwitterion or perepoxide as intermediates on the way to product formation but suggest that the rate-determining transition state occurs substantially later than has been previously suggested. (7) There is excellent correlation between rates of peracid oxidation of olefins and their singlet oxygen reaction rates, and this would be anticipated in terms of the similarities of two mechanism as shown in eq 22. 244•245 •358 Concerted ene proponents might note that though substituent effects on the rate of reaction in the general ene have not been -< (22) investigated thoroughly, relative rates obtained from competition experiments indicate that feeding electrons into the double bond increases rates here as well.16•246 In addition Foote and Denny194 have also noted that for substituted trimethylstyrenes both the photooxidation and epoxidation reactions are mildly electrophilic (p = -0.92 and -0.87, respectively).…”

“…Although the Criegee mechanism is clearly applicable to the case of allylic hydroperoxides (eq 7), it is of interest to examine an alternate possibility. In 1942, Farmer and Sundralingam104 X o o (7) u •OH suggested a mechanism for Hock-cleavage which proceeds via a dioxetane intermediate (eq 8, X = CR2). A similar process has been suggested for the thermal cleavage of a-keto114-116 (X = O), -imino117•118 (X = N-R), and -cyano119 (X = -N) hydroperoxides, as well as for the hydrogen peroxide cleavage of -diketones and -keto acids120 (X = O).…”

“…At -78 °C, however, they are stable enough to be trapped by solvent or intramolecularly by alcohol or amines on a side chain. (7) Politizer and Griffin310•377 report that the photooxidation of tetraphenylcyclopropene (147) yields diketone 152 (the cleavage product of indene dioxetane 151) as the major product. They propose that such a rearrangement requires dipolar intermediates such as zwitterion 148 which proceeds via several other intermediates (149 and 150) to the final observed product (path a).…”

Thermal generation of electronic excitation with hyperenergetic molecules

“…11, where Ø is the singlet excitation yield of the chemi-energized pro-$c = $s 0f1 I/kED] (11) cess and fl is the fluorescence yield of the chemi-energized singlet state excited cJbonyl product SK*. The quantum yield ØDC is determined experimentally for the system under study by measuring the rate of photon production, given by IC the direct cherniluminescence intensity, versus the rate of dioxetane decomposition (kCDD, as shown in eqn.…”