ISSN:
0170-2041
Schlagwort(e):
Ring transformations
;
Knoevenagel condensations
;
Epoxidation
;
Spiro[2.4]heptenones
;
Pyrazoles
;
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
Ring Transformations of 1-Oxa-5,6-diazaspiro[2.4]hept-6-en-4-ones into 4,5-Dihydro-4-hydroxy-1H-pyrazole-4-carboxylic Acid DerivativesSpiro epoxides 3 were synthesized from 1H-pyrazol-5(4H)-ones 1 by Knoevenagel condensation with acetone or benzaldehyde and subsequent epoxidation of 2 with hydrogen peroxide. 3 reacts with nucleophiles under ring transformation to 4,5-dihydro-4-hydroxy-1H-pyrazole-4-carboxylic acid derivatives 5. In three cases the intermediate 6 was isolated. 5b, c undergo by dehydrogenation with chloranil rearrangement to 4,5-dihydro-4-oxo-1H-pyrazole-5-carboxylic acid derivatives 7b, c.
Zusätzliches Material:
3 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jlac.199419940209
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