1-methoxy-3,5-diaryl-2-oxabicyclo[4.4.0]dec-3-enes from “semicyclic” 1,5-diketones

It was established that semicyclic 1,5-diketones are capable of reacting with methanol by the catalytic action of hydrogen chloride and are capable of forming 1-methoxy-3,5-diaryl-2-oxabicyclo [4.4.0]dec-3-enes — cyclic acetals that include an alkoxydihydropyran ring. In addition, 2,4-darylbicycle[3.3.1]non-2-en-9-ones, which are formed from 1,3-diaryl-3-(2-oxocyclohexyl)propan-1-ones by an intramolecular condensation of the erotonic type, are detected as side products. The possible mechanism of the reaction of 1,3-diaryl-3-(2-oxocyclohexyl)propan-1-ones with methanol in the presence of hydrogen chloride is discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 470–473, April, 1979.