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Preparation of bis‐pyrylium salts
Author(s) -
Reynolds C. A.,
Vanallan J. A.
Publication year - 1969
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.5570060504
Subject(s) - chemistry , perchlorate , perchloric acid , acetic acid , bromine , salt (chemistry) , medicinal chemistry , organic chemistry , inorganic chemistry , ion
Six methods are described for the preparation of bis‐pyrylium salts: (1) treatment of 4,4′‐bi‐2‐flavene or 4‐(4 H ‐flav‐2‐en‐4‐yl)flavylium perchlorate with triphenylmethyl perehlorate; (2) reaction of an aromatic o ‐hydroxyaldehyde and 1,4‐deacetylbenzene under acidic conditions; (3) reaction of o ‐hydroxyacetophenone, 1,4‐diacetylbenzene, perchloric acid and acetic acid; (4) reaction of a 2‐ or 4‐methylpyrylium salt with 2‐ or 4‐pyrone in the presence of phosphorus oxychloride; (5) oxidation of a 1,2‐ethanediylidenebis‐flavene or ‐thiaflavene, a bis‐flavenylidene or ‐thiaflavenylidene, and a bis‐pyranylidene or ‐thiapyranylidene by means of cupric perchlorate; and (6) reaction of 4‐methylflavylium and ‐thiaflavylium perchlorate with bromine in acetic acid.