ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A New Synthesis of 4,5-Dihydroxy-pyrazoles1-Aryl-pyrazolin-5-ones 1 are converted by Knoevenagel condensation with acetone or by reaction with 2,2-dimethyl-1,3-dioxolane 6 to 1-aryl-4-isopropyliden-pyrazolin-5-ones 2. The compounds 2 are epoxidized by hydrogen peroxide forming the spiro-epoxides 3, which can be cleaved to 4,5-dihydroxy-pyrazoles 4 under acidic conditions. 4-Acetoxy-5-hydroxy-pyrazoles 13 are formed directly, when 3 are cleaved in presence of acetic anhydride. The 3,3′,3′-trimethyl-1-(4-nitro-phenyl)-pyrazolin-4-spiro-2′-oxiran-5-one 3b undergoes rearrangement to the 1,3-dioxolo[4,5-c]pyrazole 12.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19853270106
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