N-Butyl propiolate → 5,6-Dihydro-5-oxopyrazolo[1,5-c]quinazoline-2-carboxylic acid, n-butyl ester

참여 물질

반응 단계

2.0 g (0.126 mole) of 3-diazo-oxindole is taken up in xylene (85 ml), treated with 1.2 equivalents of n-butyl propiolate (1.9 g) and refluxed under a stream of nitrogen for 17 hours in an oil bath. The light coral-colored precipitates that form are cooled and filtered off and washed with ether. Yield: 3.0 g, m.p. 190°-195°; 83.57% crude yield. The crude product is taken up in boiling absolute ethanol (250 ml), treated with activated carbon, filtered and concentrated down on a steam bath to a volume of ~75 ml. After cooling, tan-colored precipitates are filtered off and dried in a vacuum oven at room temperature for 4 hours. Yield: 2.2 g, m.p. 198°-200°.

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