Novel synthesis of 2-thienylcarbonyl-cyclohexane-1,3-dione as building block for indazolones and isoxazolones

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Summary *

A new synthetic methodology using ultrasonic treatment was applied to the C-acylation of 1,3-cyclohexanedione with thiophene-2-carbonyl-chloride to afford 3-hydroxy-2-(2-thienylcarbonyl)cyclohex-2-en-1-one (5). This compound was used as building block to prepare different bicyclic systems: tetrahydro-4H-indazol-4-ones (7a-c and 9a,b,d), and 6,7-dihydrobenzisoxazole (11) by reactions with different hydrazines and hydroxylamine respectively. Structural elucidation of all compounds was thoroughly achieved by NMR spectroscopy. Information provided by the agent in SIGEVA