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Synthetic studies of the antitumor antibiotic streptonigrin. II. Synthesis of the C‐D ring portion of streptonigrin
Author(s) -
Liao T. K.,
Wittek Philip J.,
Cheng C. C.
Publication year - 1976
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.5570130627
Subject(s) - chemistry , moiety , ring (chemistry) , base (topology) , stereochemistry , antibiotics , medicinal chemistry , organic chemistry , mathematical analysis , biochemistry , mathematics
Abstract Partial mclhylalion of gallopropiophenonc ( 4 ) followed by benzylation and base‐catalyzed condensation with ethyl acetate yielded 3‐(2‐benzyloxy‐3,4‐din]etlK>xy)benzoyl‐2‐butanonc ( 6 ). Animation of the latter and subsequent base‐catalyzed cyclization with ethyl cyanoacetate gave 4‐(2‐benzyloxy‐3,4‐dimethoxy)phenyl‐5,6‐dimethyl‐2‐oxo‐1,2‐dihydropyridine ( 8 ). Removal of the 2‐oxo group of 8 through chlorination and dechlorination and stepwise conversion of the 5‐cyano and 2‐methyl groups into the 5‐amino and 2‐carboxylic acid groups, respectively, with introduction and removal of protecting groups at proper stages, yielded the C‐D ring moiety of the antitumor antibiotic streptonigrin.