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Benzimidazole condensed ring systems. 5 . Studies on the Synthesis of Pyrimido[1,6‐α]benzimidazole‐1,3(2 H ,5 H )‐diones
Author(s) -
Badawey ElSayed A. M.,
Rida Samia M.,
Soliman Farid S. G.,
Kappe Thomas
Publication year - 1989
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.5570260532
Subject(s) - chemistry , benzimidazole , sulfuryl chloride , ring (chemistry) , isocyanate , phosphoryl chloride , medicinal chemistry , alkylation , chloride , organic chemistry , catalysis , polyurethane
The reaction of ethyl 1 H ‐benzimidazole‐2‐acetate (1) with methyl or ethyl isocyantes 2a,b resulted in excellent yields of the respective 2‐methyl‐ or 2‐ethylpyrimido[1,6‐ a ]benzimidazole‐1,3(2 H ,5 H )‐diones 3a,b , while the reaction of 1 with phenyl isocyanate (2c) gave, unexpectedly, ethyl 2‐(1‐phenylcarbamoyl‐1 H ,3 H ‐benzimidazol‐2‐ylidene)‐2‐phenylcarbamoylacetate (4). Alkylation of 3 with trimethyl or triethyl phosphates 5a,b led to the 5‐methyl or 5‐ethyl derivatives 6a‐d . Chlorination of 6 with sulfuryl chloride afforded the 4‐chloro derivatives 7a‐d.