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2,5‐Disubstituted Pyrazolo[4,3‐ c ]cinnolin‐3‐ones
Author(s) -
Beshore Douglas C.,
Johnson Adam W.,
DiPardo Robert M.,
Pitts Daniel R.,
Cofre Victoria,
Kuduk Scott D.
Publication year - 2017
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.2744
Subject(s) - chemistry , substituent , ring (chemistry) , intramolecular force , aryl , alkylation , medicinal chemistry , stereochemistry , combinatorial chemistry , organic chemistry , alkyl , catalysis
Complementary strategies to 2,5‐disubstituted pyrazolo[4,3‐ c ]cinnolin‐3‐ones are reported herein, providing late stage substituent introduction at either the 2‐ or the 5‐position. Treating a readily prepared 4‐thiocinnoline ester with substituted hydrazines afforded late stage access to the 2‐position, while late stage substituent introduction at the 5‐position was achieved via two different strategies: alkylation of 4‐hydrazonopyrazol‐3‐ones, followed by a ring‐closing intramolecular S N Ar tactic and direct reaction of 5‐(2‐fluorophenyl)‐2,4‐dihydro‐3 H ‐pyrazol‐3‐ones with aryl diazonium salts, followed by cyclization . The strategies described herein provide practical and general methods to prepare 2,5‐disubstituted pyrazolo[4,3‐ c ]cinnolin‐3‐ones.