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Please login or sign up for a free trial to access the full content. Variation 2: By Photolysis of 1a,3a,3b,9a,9b,11a-Hexahydrocycloocta[3′,4′]cyclo­buta[1′,2′:5,6]cycloocta[1,2-b]oxirene and Similar Compounds

DOI: 10.1055/sos-SD-017-01530

Borzilleri, R. M.Science of Synthesis, (2004171019.

As in the similar case of oxa[13]annulene (vide supra), the tetracyclic epoxide 1a,3a,3b,9a,9b,11a-hexahydrocycloocta[3,4]cyclobuta[1,2:5,6]cycloocta[1,2-b]oxirene (194) at 80°C in diethyl ether undergoes photolysis on irradiation with light from a low-pressure UV lamp. The product is an oxa[17]annulene, oxacycloheptadeca-2,4,6,8,10,12,14,16-octaene (195) (Scheme 49).[‌134‌] Exposure of the isomeric epoxide 196 to the same reaction conditions leads to a second oxa[17]annulene configurational isomer. In related work, irradiation of the regioisomeric aziridines 197 and 198 in diethyl ether at low temperature with a low-pressure UV lamp affords a mixture of three thermally non-interconvertible geometric isomers 199,[‌135‌] and photolysis of the tetracyclic azide 200 at 80°C under high dilution conditions in pentane gives the thermally stable, dark green, crystalline aza[18]annulene (201) (Scheme 49).[‌136‌]

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