Synthesis of 4-carbethoxy-4<i>H</i>-3-substitutedisoxazol-5-ones and their conversion into novel spiroheterocycles

68-70Interaction of diethyl α-acyl/aroylmalonates 1 with hydroxylamine hydrochloride 2 afford 4-carbethoxy-4H-3-substituted isoxazol-5-ones 3 and 3-substitu ted-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-diox(l-9-oxa-7-substituted-l-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