Ammonia → 1-(2,6,6-Trimethyl-1-cyclohexen-1-yl)-2-buten-1-one

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Reaction Steps

To a mixture of liquid ammonia (500 ml), tetrahydrofuran (30 ml), tert-butanol (2.796 g) and 3-methyl-5-[2,6,6-trimethyl-cyclohex-1-en-1-yl]-isoxazole (2.593 g; 12.65 millimoles), kept under stirring, there was added sodium metal until the solution acquired a steady blue colour. The reaction mixture was stirred for 15 more minutes, solid ammonium chloride was added thereto until complete discolouration, and the ammonia was then evaporated under a stream of argon. After having added 50 ml of ether and 300 ml of a concentrated ammonium chloride solution in water, the mixture was extracted with two fractions of 300 ml of ether and 150 ml of chloroform, respectively. The combined organic extracts were dried over magnesium sulphate, concentrated under reduced pressure and dissolved in 50 ml of toluene containing traces of p-toluene-sulphonic acid. The thus obtained mixture was refluxed for 24 hours, concentrated in vacuo and then distilled to yield 2.074 g (yield 84%) of 2,6,6-trimethyl-1-[but-2-enoyl]-cyclohex-1-ene; b.p. 55°/0.04 Torr. The analytical data of the obtained product were identical with those of a pure sample prepared by one of the known methods.

Provenance & Evidence