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Photocyclization reactions. Part 3 . Synthesis of naphtho[1,8‐ bc ]‐furans and Cyclohepta[ cd ]benzofurans using photocyclization of 8‐alkoxy‐1,2,3,4‐tetrahydro‐1‐naphthalenones and 4‐alkoxy‐6,7,8,9‐tetrahydro‐5 H ‐benzocyclohepten‐5‐ones
Author(s) -
Sharshira Essam Mohamed,
Iwanami Haruki,
Okamura Mutsuo,
Hasegawa Eietsu,
Horaguchi Takaaki
Publication year - 1996
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570330104
Subject(s) - chemistry , benzofuran , furan , alkoxy group , substituent , ring (chemistry) , acetonitrile , medicinal chemistry , stereochemistry , organic chemistry , alkyl
Photocyclization reactions were carried out on 8‐alkoxy‐1,2,3,4‐tetrahydro‐1‐naphthalenones (six‐membered ring ketones) 4a‐g and 4‐alkoxy‐6,7,8,9‐tetrahydro‐5 H ‐benzocyclohepten‐5‐ones (seven‐membered ring ketones) 5a ‐e in acetonitrile. Irradiation of 4a‐f gave rearranged naphthyl alcohols 8a‐f as major products. In the case of 4g , 2a,3,4,5‐tetrahydronaphtho[1,8‐ bc ]furan‐2a‐ol 6g was obtained. In contrast, irradiation of 5a‐e afforded 2,2a,3,4,5,6‐hexahydrocyclohepta[ cd ]benzofuran‐2a‐ols 9a‐e in good yields. The difference in reactivities between 4a‐g and 5a‐e is attributed to the conformation of six‐ and seven‐membered rings. Conformational and substituent effects in cyclization step of 1,5‐biradicals are discussed along with reaction pathways.