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Streptonigrin and related compounds IV. Precursors for the a‐ring
Author(s) -
Rao Koppaka V.,
Kuo HsienSaw
Publication year - 1979
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.5570160630
Subject(s) - chemistry , tricyclic , ring (chemistry) , condensation , stereochemistry , combinatorial chemistry , organic chemistry , physics , thermodynamics
The synthesis of streptonigrin or its tricyclic (ABC) analogues by the Friedlander condensation requires a 2‐nitrobenzaldehyde with all the necessary functionalities. A number of alternative syntheses are examined. It is shown that oxidation of 8‐amino‐5,6‐dimethoxy‐2,2‐pyridylquinoline leads to 8‐amino‐2,2‐pyridylqunoline‐5,6‐dione instead of 6‐methoxy‐2,2‐pyridylquinoline‐5,8‐dione. The synthesis of two useful precursors: 4‐bromo‐3‐hydroxy‐5,6‐dimethoxy‐2‐nitrobenzaldehyde and 4‐bromo‐3‐hydroxy‐5‐methoxy‐2‐nitrobenzaldehyde is described.