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Ring closure and rearrangement reactions of 4‐azido‐2‐oxoquinoline‐3‐carboxylates and 4‐azidocoumarin‐3‐carboxylates
Author(s) -
Stadlbauer Wolfgang,
Prattes Susanne,
Fiala Werner
Publication year - 1998
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.5570350322
Subject(s) - chemistry , ring (chemistry) , closure (psychology) , thermal decomposition , medicinal chemistry , decomposition , reaction conditions , organic chemistry , catalysis , economics , market economy
4‐Azido‐2‐oxoquinoline‐3‐carboxylates and 4‐azidocoumarin‐3‐carboxylates 6 , which were obtained from the corresponding 4‐hydroxy derivatives 1 via 4‐tosylates 2 or 4‐chloro compounds 4 , cyclized upon thermolysis to 3‐alkoxyisoxazolo[4,3‐ c ]quinolin‐4(5 H )‐ones or the corresponding coumarins 8 , whereas at slightly higher temperatures a 3‐ O , 4‐ O ‐rearrangement took place to give the 4‐alkoxy‐isoxazolo[4,3‐ c ]‐quinolin‐3‐ones and the corresponding coumarins 9. The necessary reaction conditions could be obtained easily with the help of differential scanning calorimetry.