Highly condensed polycyclic systems. Part IV. Action of concentrated sulphuric acid on 1,2,4,5-tetrachloro-3,3-ethylenedioxytetracyclo-[3,2,0,0,0]heptane: a novel rearrangement of a quadricyclanone acetal

Abstract

Treatment of 1,2,4,5-tetrachloro-3,3-ethylenedioxytetracyclo[3,2,0,0,0]heptane (II; X = [graphic omitted], R¹= R²= Cl) with concentrated sulphuric acid results in a novel rearrangement to give 6,7-dichloro-3,4-ethylenedioxybicyclo[3,2,0]hepta-3,6-dien-2-one (IV). Similar treatment of 1,2,3,4-tetrachloro-7,7-ethylenedioxybicyclo[2,2,1]hepta-2,5-diene (I; X = [graphic omitted], R = H) yields 2-hydroxyethyl 2,3,4-trichlorobenzoate (X; X = OH).

Zinc in glacial acetic acid reacts with the 1,2,3,4-tetrachloro-5,5-ethylenedioxycyclopentadiene dimer (XII; X = [graphic omitted], R = Cl), effecting selective replacement of two chlorine atoms by hydrogen, and affording 1,3,4,7,8,9-hexachloro-5,5:10,10-bis(ethylenedioxy)tricyclo[5,2,1,0^2,6]deca-3,8-diene (XII; X = [graphic omitted] R = H).