engleski

Photochemical and thermal intramolecular 1, 3-dipolar cycloaddition reactions of new o-stilbene-methylene-3-sydnones and their synthesis

New trans- and cis-o-stilbene-methylene-sydnones 3a, b were synthesized by transforming the trans- and cis-o-aminomethylstilbene derivative, obtained by reduction of corresponding o-cyano derivatives, into glycine-ester derivatives (43 and 31% yield) followed by hydrolysis (90 and 96% yield), nitrosation and ring closure with acetic acid anhydride (30 and 40% yield). They have been submitted to photochemical and thermal intramolecular 3+2 cycloadditions affording diverse heteropolycyclic compounds. Photochemical reaction afforded cis-3-(4-methylphenyl)-3a, 8-dihydro-3H-pyrazolo[5, 1-a]isoindole (11, 12.5% yield) and trans-3-(4-methylphenyl)-3a, 8-dihydro-3H-pyrazolo[5, 1-a]isoindole (12, 5% yield). Thermal reaction afforded 3-(4-methylphenyl)-3, 3a, 8, 8a-tetrahydroindeno[2, 1-c]pyrazole (14, 50% yield) and 11-(4-methylphenyl)-9, 10-diazatricyclo[7.2.1.02, 7]dodeca-2, 4, 6, 10-tetraene (15, 22% yield).

[3+2] cycloaddition ; sydnones ; nitrile imines ; pyrazoles ; isoindoles

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