Ozonolysis of tetrahydrophthalimides (cyclohex-4-ene-1,2-dicarboximides): a sterically dependent unsymmetrical oxidative cleavage reaction

Abstract

Ozonolysis of cis-tetrahydrophthalimide or cis-N-phenyltetrahydrophthalimide in anhydrous methanol gives moderate yields of the unsymmetrical oxidative cleavage products, cis-3-(2,2-dimethoxyethyl)-4-methoxycarbonylmethylpyrrole-2,5(3H,4H)-dione and cis-3-(2,2-dimethoxyethyl)-4-methoxycarbonylmethyl-1-phenylpyrrole-2,5(3H,4H)-dione. In contrast to these results, the ozonization in methanol of the methylene-bridged analogues, endo-4-azatricyclo[5.2.1.0^2,6]dec-8-ene-3,5-dione and endo-4-phenyl-4-azatricyclo[5.2.1.0^2,6]dec-8-ene-3,5-dione, gives the symmetric oxidative cleavage products, endo,endo,cis-6,8-bis(dimethoxymethyl)-3-azabicyclo[3.3.0]octane-2,4-dione and endo,endo,cis-6,8-bis(dimethoxymethyl)-3-phenyl-3-azabicyclo[3.3.0]octane-2,4-dione. The latter bis-acetal could be converted under hydrolytic conditions into two other dialdehyde derivatives, cis,exo-8,10-dimethoxy-cis,endo-4-phenyl-9-oxa-4-azatricyclo-[5.3.1.0^2,6]undecane-3,5-dione and trans-8,10-dihydroxy-cis,endo-4-phenyl-9-oxa-4-azatricyclo[5.3.1.0^2,6] undecane-3,5-dione. All structural assignments were confirmed with the aid of natural abundance 25.16 MHz carbon-13 magnetic resonace spectra including multiplicities and ¹³C–¹H coupling constants.