Reaction of Epoxyketones with Hydrogen Peroxide—Ethane‐1,1‐dihydroperoxide as a Surprisingly Stable Product

Abstract

Oxidation of organic compounds with hydrogen peroxide has attracted attention for a long time and has been attributed to green chemistry. We used hydrogen peroxide in reactions with cyclic alcohols and observed unusual rearrangement reactions under ring enlargement giving new hydroperoxides and peroxides. [1][2][3] In this way we also obtained aliphatic primary geminal dihydroperoxides.[2] We report here on reactions of cyclic epoxyketones with hydrogen peroxide. Such epoxides are usually synthesised by the Weitz-Scheffer reaction, that is, by reaction of a,b-unsaturated ketones with H 2 O 2 under basic conditions.[4] We treated such products with 70 % H 2 O 2 in the presence of catalytic amounts of camphor sulfonic acid at room temperature.Substituted 6-ring epoxyketones 1 at the 3-position gave mixtures of products, interestingly consisting of geminal dihydroperoxides 2, dicarboxylic acids 3, carboxylic acids 4 and ketocarboxylic acids 5 (Table 1, Scheme 1).The geminal dihydroperoxides 2 show significant signals in the NMR spectra. [2,[5][6][7] Thus, the hitherto unkown ethane-1,1-dihydroperoxide (2 a) exhibits a signal at 107.9 ppm in the 13 C NMR spectrum and one typical hydroperoxide-H signal (intensity two protons) at 9.71 ppm in the 1 H NMR spectrum. In combination with the HR-ESI MS result, the structure of 2 a could be proven unambiguously. The geminal dihydroperoxide 2 a has the highest content of peroxide oxygen (68 %) relative to hitherto known organic peroxides and hydroperoxides.The so-called triacetone triperoxide (6; 43 % peroxidic oxygen) and methylhydroperoxide (7; [8] 66.7 %) were reported as highly explosive compounds. Despite the very high oxygen content compound 2 a is remarkably stable. It can be kept at room temperature for several days and at À20 8C for several weeks without decomposition. Thermogravimetric investigations (see Supporting Information) showed decomposition in the temperature range 60-130 8C with the highest decomposition rate at about 105 8C. Using differently substituted epoxyketones as reactants we were also able to isolate and characterise propane-1,1-dihydroperoxide (2 b), which is not yet described in literature, and to obtain benzylidenedihydroperoxide (2 c). The latter was previously described by using a different method from the reaction of benzaldehyde with H 2 O 2 .[ 4 [%] [b] 5 [%] [b]

The Multiple Reactions in the Monochlorodimedone Assay: Discovery of Unique Dehalolactonizations under Mild Conditions

“…IR: =534, 610, 874, 907, 926, 968, 1053, 1119, 1136, 1196, 1231, 1288, 1360, 1375, 1418, 1468, 1717, 1790, 2876, 2934, 2969, 3028, 3565 cm −1 . The 1 H and 13 C NMR values are consistent with those reported in the literature …”

Rearrangements of organic peroxides and related processes

“…The acid-catalyzed Baeyer–Villiger oxidation of cyclic epoxy ketones 22 produces lactones of type 23 , which convert into carbenium ions 24 in the presence of the acid. Subsequently, these ions can be transformed with participation of H 2 O 2 through three different pathways into dihydroperoxides 25 , dicarboxylic acids 28 , carboxylic acids 26 , and keto carboxylic acids 27 ( Scheme 7 , Table 1 ) [ 223 ].…”

“…The oxidation of isophorone oxide ( 29) is an industrial process for the production of dimethylglutaric acid 30 ( Scheme 8 ) [ 223 ].…”

Enantio‐ and Diastereoselective Synthesis of exo‐Peroxyacetals: An Organocatalyzed Peroxyhemiacetalization/oxa‐Michael Addition Cascade

“…[9] However, to the best of our knowledge,t he synthesis of enantio-and diastereoselective exo-peroxyacetals has not yet been established. [13] We envisioned ap eroxyhemiacetalization/oxa-Michael addition cascade of the substrate A (Scheme 1), where the reversibly formed peroxyhemiacetal intermediate B could be converted into the oxa-Michael adduct C by adynamic kinetic resolution process catalyzed by ac hiral amino-thiourea/ squaramide catalyst. [14,15] Nevertheless,o vercoming the direct conjugate addition of peroxide on an a,b-unsaturated moiety remains apotential barrier to this strategy.…”