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Synthesis of new heterocyclic phenols: 9‐Hydroxypyrido[1,2‐ a ]pyrimidin‐4‐one and Derivatives
Author(s) -
Dennin F.,
Blondeau D.,
Sliwa H.
Publication year - 1991
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.5570280521
Subject(s) - chemistry , hydrogenolysis , phenol , condensation , phenols , ether , organic chemistry , diethyl ether , medicinal chemistry , catalysis , physics , thermodynamics
9‐Hydroxypyrido[1,2‐ a ]pyrimidin‐4‐one ( 5 ) was prepared by condensation of 2‐amino‐3‐hydroxypyridine with isopropylidene aminomethylenemalonate. The reaction first led to an enaminoester intermediate which underwent cyclization by heating at 250° affording the new heterocyclic phenol 5 . A similar condensation performed on 2‐amino‐3‐benzyloxypyridine yielded the corresponding benzylic ether which can be easily debenzylated to 5 by hydrogenolysis. Furthermore 2‐amino‐3‐benzyloxypyridine condensed with diethyl ethoxymethylenemalonate gave 9‐benzyloxy‐3‐ethoxycarbonylpyrido[1,2‐ a ]pyrimidin‐4‐one which was also debenzylated to the corresponding free phenol.