Diisopropylamine → methyl 2-(5-oxo-5H-dibenzo[a,d]cyclohepten-2-yl)acrylate

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Reaction Conditions

Reaction Steps

1.25 Ml. of 1.6 molar n-butyllithium in hexane is added to a solution of 0.280 ml. of diisopropylamine in 30 ml. of tetrahydrofuran. The solution is cooled to -80° C and 0.556 g. of methyl (5-oxo-5H-dibenzo[a,d]cyclohepten-2-yl)acetate is added. After 10 minutes 0.38 ml. of hexamethylphosphoric triamide is added. The cooling bath is removed and formaldehyde vapor, entrained in nitrogen, is passed over the solution until it becomes colorless. Water and ether are then added and the organic layer is washed with dilute hydrochloric acid, saturated sodium chloride solution, then dried and evaporated. The residue is chromatographed on 10 g. of silica gel, eluting with hexane: ethyl acetate (5:1) to isolate methyl 2-(5-oxo-5H-dibenzo[a,d]cyclohepten-2-yl)acrylate (m.p. 153°-156° C). 0.02 G. of this compound is refluxed under nitrogen in 5 ml. of water, 2 ml. of ethanol and 0.5 ml. of saturated sodium carbonate solution for 4 hours. The mixture is cooled, washed with ether and acidified with dilute hydrochloric acid, then extracted with ethyl acetate and the extract dried and evaporated to yield 2-(5-oxo-5H-dibenzo[a,d]cyclohepten-2yl)acrylic acid (m.p. 232°-235° C).

Provenance & Evidence