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Ring transformation reactions of C ‐nucleosides: Facile synthesis of pyrazolo[1,5‐ a ]pyrimidine and pyrazolo[1,5‐ a ]triazine C ‐nucleosides
Author(s) -
Chu C. K.,
Suh J. J.,
Mesbah M.,
Cutler S. J.
Publication year - 1986
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.5570230209
Subject(s) - synthon , chemistry , pyrimidine , sodium ethoxide , triazine , derivative (finance) , ring (chemistry) , organic chemistry , bicyclic molecule , medicinal chemistry , stereochemistry , ethanol , financial economics , economics
1,3‐Dimethyluracil ( 1 ), a versatile synthon for the synthesis of various heterocycles, reacted readily with 3‐aminopyrazoles 2 in sodium ethoxide to give pyrazolo[1,5‐ a ]pyrimidines 3 . Under similar conditions, 3‐aminopyrazole C ‐nucleosides 4 and the synthon 1 gave a mixture of pyrazolo[1,5‐ a ]pyrimidine C ‐nucleosides, which was separated on a silica gel column. Attempts to remove the protecting groups yielded pyranose derivative 10 . Another synthon 1,3‐dimethyl‐5‐azauracil and 3‐aminopyrazoles 12 gave pyrazolo[1,5‐ a ]triazines 13 . In a similar reaction with 3‐aminopyrazole C ‐nucleosides 4 gave the corresponding pyrazolo[1,5‐ a ]‐triazine C ‐nucleosides 14 and 15 .