Epoxidation of hexacyclo[9.2.1.0^2,10.0^3,8.0^4,6.0^5,9]tetradecanes under thermal and microwave irradiation

Epoxidation of alkenes is an important process in both industry and academia because epoxides are versatile intermediates in organic synthesis and they are widely used as monomers to prepare functional polymers. The presence of strained, volumetric fragments in the structure of the initial monomers makes it possible to obtain polymers with increased strength and heat resistance. Therefore, the synthesis of new compounds containing saturated three-membered oxygen-containing heterocycles is an important and urgent task of modern organic chemistry.

In this work, we carried out the epoxidation of hexacyclic dimers of norbornadiene − exo-exo-, exo-endo-, endo-exo-, endo-endo-hexacyclo[9.2.1.0^2,10.0^3,8.0^4,6.0^5,9]tetradec-12-ene under the influence of Mo-, V-, W-containing catalysts. The following oxidizing agents were tested: 4-methoxy-, 4-ethoxy-, pentafluoro-, 3-chloroperbenzoic acids, and as studies have shown, pentafluoro- and 3-chloroperbenzoic acids are the most effective. The reactions were carried out in chloroform under conditions of thermal (40-120 °C) and microwave irradiation (0.5-1 kW, 40-60 °C). It was found that when conducting experiments at room temperature for 8−48 hours, the conversion does not exceed 15%. The maximum yields (64−78%) are observed when carrying out reactions under conditions: 100 ℃, 8−12 hours, in a sealed ampoule placed in stainless steel autoclave. Interesting results were obtained when conducting experiments under microwave irradiation conditions. The maximum yields (92-96%) of the target products were observed when conducting experiments under the following conditions: 1 kW, 40 °C, 30 min. As a result of the reaction, previously undescribed 12,13-epoxyhexacyclotetradecanes are formed, the structure of which was proven by one- and two-dimensional NMR spectroscopy.