Synthesis of 4-carbethoxy-4H-3-substituted-isoxazol-5-ones and their conversion into novel spiroheterocycles

摘要

Interaction of diethyl #alpha#-acyl/aroylmalonates 1 with hydroxylamine hydrochloride 2 afford 4-carbethoxy-4H-3-substituted-isoxazol-5-ones 3 and 3-substituted-4H-5-oxo-isoxazol-4-carboxylic acids 4. Bromination of 3 affords 4-bromo derivatives 5, which with thiocarbamides, 4-substituted thiosemicarbazides give 2-alkyl/arylimino-4, 9-dioxo-3, 7-diaza-8-oxa-6-substituted-1-thia-(3H)-spiro[4.4]nonan-6-enes 7 and 2-alkyl/arylimino-5, 10-dioxo-9-oxa-7-substituted-1-thia-3, 4, 8-triaza-(3H, 4H)-spiro[5.4]dec-7-enes 8. Characterisation of the products has been done on the basis of spectral (IR, ~1H NMR and ~13C NMR) data.