Pyrazolones lactones

Many other heterocycles have been prepared following intramolecular nucleophilic cleavage strategies, like pyrazolones [102,103], benzimidazoles [104], indoles [105], quinazoline-2,4-diones [106], quinolinones [107], tetramic acids [108], oxa-zolidinones [82] and lactones [109, 110]. 

Dehydro-ascorbic acid osazones can be rearranged by ring opening of the lactone which upon cyclization gave the respective pyrazolones which can be converted into different functionalized derivatives [49,50,56-60]. 

The Hantzsch reaction has also been incorporated in a multi-component reaction described by Rao et al. to produce 2-pyrazol 4-yl-substituted diiazole system in one step. The reaction involves a one-pot cyclization to form thiazole, pyrazolone and cyclopropane rings via the reaction of aryl bromomethylketonewith, thiosemicarbazide, and a-acetyl-y-butyro lactone in phosphorus oxychloride. 

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