Synthesis of Epimethanetriyloxazoloand Epimethanetriylimidazobenzazocinones and -benzazoninones from syn- and anti-Atropisomers of N-Acyl-N-[2-(cycloalk-2-en-1-yl)-6-methylphenyl]glycines

The major product of intramolecular [3 + 2]-cycloaddition of munchnones generated by heating syn- and anti-atropisomers of N-acetyl-N-[2-(cyclopent-2-en-1-yl)-6-methyl-, 2,4-dimethyl-, 2,5-dimethylphenyl)- and N-acetyl-N-[2-(cyclohex-2-en-1-yl)-6-methylphenyl]glycines with acetic anhydride was that formed from the anti isomer. Isomeric glycine derivatives having no methyl group in the ortho position of the aromatic ring gave rise to (1S*,3aR*,4S*,7S*,13S*)-1-methyl- and (1S*,3aR*,4S*,7S*,13S*)-3a-acetyl-1-methyl-4,5,6,7- tetrahydro-1,4,7-epimethanetriyl[1,3]oxazolo[3,4-a][1]benzazocin-3(3aH)-one as the major product. Treatment of 1,11-dimethyl- and 1,9,11-trimethyl-4,5,6,7-tetrahydro-1,4,7-epimethanetriyl[1,3]oxazolo[3,4-a][1]benzazocin- 3(3aH)-ones with methylamine in methanol on heating in a sealed ampule afforded epimethanetriylimidazobenzazocinones, whereas acid-stable compound with a methanocyclopenta[c]quinoline skeleton was formed under similar conditions from the 1,8,11-trimethyl analog.