1,2,4,5-Tetroxans

Trioxane 210 has been used as a model system by Gu and coworkers to study the antimalarial drug artemisinin 211 (Scheme 137) [97CPL234, 99JST103]. It is the boat/twist form rather than the chair conformer of 210 that describes the subunit in 211. Moreover, geometric parameters and vibrational frequencies can only reliably be computed at the DFT level and by post-Hartree-Fock methods. B3-LYP/6-31G calculations on the conformers of 3,3,6,6-tetramethyl-1,2,4,5-tetroxane show that the chair conformer is stabilized with respect to the twisted conformer by about -2.8 kcal/mol [00JST85]. No corresponding boat conformer was found. 

The thermolysis of a variety of 1,2,4-trioxanes in methanol has been followed by mass spectrometry and provided evidence of the corresponding products. A smdy of the thermal decomposition of 3,6-diphenyl-1,2,4,5-tetroxane in toluene and methanol revealed a significant solvent effect that supported a homolytic stepwise mechanism instead of a concerted process. ... 

Recently, the enthalpies of combustion and sublimation were measured for formaldehyde diperoxide, i.e. 1,2,4,5-tetroxane , from which the enthalpies of formation could be derived. These results were shown to be in good agreement with quantum chemical... 

An important paper by Salomon, Clennan and coworkers on dialkyl peroxides , where also one ozonide was reported, appeared in 1985. In this paper, a correlation among and 0 chemical shifts was established, and the influence of several factors like concentration, temperature, solvent and, naturally, chemical structure was thoroughly studied but confined to dialkyl peroxides. There was a gap of several years before the appearance of a further note reporting data of seven 1,2,4-trioxolanes (ozonides), 1-4, and of the 1,2,4,5-tetroxane 5. Their 0 NMR data are given in Table 2. Spectra were obtained at natural isotopic abundance, in toluene at 27 °C. 

The 1,2,4,5-tetroxane products 199a and 199b in Scheme 7 were identified and their transformation to other products could be followed by H NMR spectroscopy . 

A related study54 of 3,6-diphenyl-1,2,4,5-tetroxane resulted in enthalpies of formation of the solid and gaseous species of 134.0 1.3 and 99.7 1.3 kj mol 1. Again, while computational theory and experiment are in good agreement, the sublimation enthalpy of 34.3 kj mol 1 seems too low. We would have suggested a lower bound of ca 71 kj mol 1 based on our enthalpy of vaporization estimation approach given above. 

Diethylidene Diperoxide Diacetaldehyde Peroxide Acetaldehyde Superoxide or Ethylidene Peroxide (called 3.6-Dimethyl-1.2.4.5-tetroxan or Diathyliden-diperoxyd in Ger),... 

Sulfonyl diisocyanate gives the thiatriazine (577) on treatment with ammonia (58CB1200). Ketones and 86% hydrogen peroxide give 3,3,6,6-tetrasubstituted 1,2,4,5-tetroxanes (578) (80JCR(S)35). 

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