Ozonolysis of tetramethoxyethene

Ozonolysis of tetramethoxyethene 1 produces 20–40% of dimethyl carbonate 3, 35–60% of methyl trimethoxyacetate 7, and 20–35% of the dioxetane 8 of 1. Yields vary with initial concentration of 1, temperature, and solvent. Singlet oxygen is produced, which reacts with 1 to form 8 and can be trapped with 2,5-dimethylfuran. No evidence for the formation of the molozonide of 1 was obtained. Up to 2.5 moles of 1 are consumed per mole of ozone. Ozonolysis of a mixture of 1 and 2,3-dimethyl-2-butene 12 gave the epoxide of 12 and three times the expected amount of the allylic hydroperoxide of 12. A competing radical chain oxidation reaction is proposed to account for these products and the stoichiometry of the ozonolysis. The initial reaction in the ozonolysis of 1 is proposed to be an electron transfer reaction that is calculated to be exothermic by > 35 kcal/mol. The resulting radical ions initiate the radical chain oxidation and combine to form the oxygenated epoxide 9 of 1. Loss of singlet oxygen from 9 forms the epoxide 10, which rearranges to 7. At −95 °C the zwitterion from 10 is trapped by CD3OD to produce a mixture of 7 with one α OCD3 group and pentamethoxyethanol with one β OCD3 group from which a CH3OD group is lost at ~ −10 °C to form more deuterated ester.