Aromatic carboxylic acids are found
to undergo reactions with isocyanates,
wherein triflic acid promotes the formation of aromatic imide products
in fair to good yields. It is proposed that the carboxylic acid group
directs the isocyanate electrophile to the ortho-position.
This is thought to occur by the formation of a temporary carbamic
acid anhydride group, which cleaves upon ortho-functionalization.
A series of imide products are synthesized, and the synthesis of a
potential selective inhibitor of tyrosyl DNA phosphodiesterase II
is performed.
Ferrocenes undergo one-step carboxamidation by reaction with isocyanates in CFSOH solution. The chemistry is most efficient in excess superacid, and it has been accomplished with aryl and aliphatic isocyanates. In conversions with ferrocene carboxylic acids, isocyanates provide imides in good yields. A mechanism for this conversion is suggested involving carbamic acid anhydride formation and subsequent intramolecular reaction at the substituted cyclopentadienyl ring.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.