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Reaction of ethyl 3‐ethoxymethylene‐2,4‐dioxovalerate and ethyl ethoxymethyleneoxaloacetate with 3‐aminopyrazole analogs. Synthesis and chemistry of 3,6,7‐trisubstituted pyrazolo[1,5‐ a ]pyrimidine derivatives
Author(s) -
Kurihara Takushi,
Nasu Keiko,
Ishimori Fumiko,
Tani Tsutomu
Publication year - 1981
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.5570180130
Subject(s) - chemistry , diazomethane , phenylhydrazine , ethyl diazoacetate , yield (engineering) , acetic acid , pyrimidine , medicinal chemistry , catalysis , ring (chemistry) , organic chemistry , reactivity (psychology) , stereochemistry , medicine , materials science , alternative medicine , pathology , cyclopropanation , metallurgy
The chemical reactivity of a series of 3‐substituted‐6‐acetyl‐7‐carbethoxypyrazolo[l,5‐ a ]pyrimidines ( 6a,b,c ) and 3‐substituted‐6,7‐dicarbethoxypyrazolo[1,5‐ a ]pyrimidines ( 7a,b,c ), prepared by the condensations of the 3‐aminopyrazole analogs ( 3a,b,c ) with ethyl 3‐ethoxymethylene‐2,4‐dioxovalerate ( 1 ) or ethyl 3‐ethoxymethyleneoxaloacetate ( 2 ), was investigated. Catalytic hydrogenation of 6 or 7 afforded 4,7‐dihydro derivatives ( 8 or 9 ). Treatment of 6a,b with acetic acid and water underwent ring transformation into 6 H ‐pyrazolo[1,5‐ a ][1,3]diazepin‐6‐ones ( 17a,b ). By treatment with phenylhydrazine compounds of type 6 underwent cyclization to yield 2 H ‐dipyrazolo[1,5‐ a :4′,3′‐ e ]pyrimidines ( 18a,b,c ). Compounds 6 or 7 were treated with an excess of diazomethane at room temperature to give 5‐methyl‐6 H ‐cyclopropa[5a,6a]pyrazolo‐[1,5‐ a ]pyrimidines ( 24 and 25 ) in excellent yields. However, when this reaction was carried out under ice cooling, only compounds of type 23 were isolated. Reaction of 6a with ethyl diazoacetate is also described.