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Furan derivatives. Part 10 . Synthesis of cyclohepta[ cd ]benzofuran
Author(s) -
Horaguchi Takaaki,
Hasegawa Eietsu,
Shimizu Takahachi,
Tanemura Kiyoshi,
Suzuki Tsuneo
Publication year - 1989
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.5570260218
Subject(s) - chemistry , benzofuran , acetic anhydride , medicinal chemistry , acetic acid , furan , protonation , trifluoroacetic acid , catalysis , trifluoroacetic anhydride , formylation , acetonitrile , ethyl acetoacetate , cinnoline , sodium methoxide , organic chemistry , ion
Abstract Cyclohepta[ cd ]benzofuran 2 was synthesized by heating (5‐oxo‐5 H ‐benzocyclohepten‐4‐yloxy)acetic acid 16 with sodium acetate in acetic anhydride or by photocyclization of 16 in acetonitrile. Several reactions of cyclohepta[ cd ]benzofuran 2 were examined. Protonation of 2 with trifluoroacetic acid occurred at the 2‐position to give a tropylium ion 17 . Catalytic hydrogenation of 2 with palladium on charcoal proceeded smoothly to give tetrahydrocyclohepta[ cd ]benzofuran 18 . The Diels‐Alder reaction of 2 with tetracyano‐ethylene produced an adduct 19 . Formylation of 2 with phosphorus oxychloride and dimethylformamide occurred easily at the 2‐position to afford compound 20 . Cyclohepta[ cd ]benzofuran 2 has both properties of heptafulvene and benzofuran.