Sulfuric Acid → HCID 12832713, compound

Participants

Reaction Steps

1-Carboxy-β-phenyl-4-piperidinehydracrylic acid diethyl ester (60 g, 0.17 mol; mp 73°-75° C.), prepared by the general procedures described in Example 1, is added portionwise to a stirred mixture of 600 ml of concentrated sulfuric acid, and stirring at room temperature is continued for 4 hours. The solution is poured onto ice, and the mixture is extracted with a copious volume of diethyl ether. The ether extract is washed with water, dried and evaporated; the residue is collected as a solid (34 g) with the aid of a small volume of ether. This product mixture is purified by partition chromatography on a Celite® diatomaceous earth column developed with a hexane-methanol solvent system. The two main fractions separated on the partition column are each, in methylene chloride solution, passed through a short column of alumina (Woelm, Activity II) and the columns are eluted with methylene chloride and then with ethylacetate. Evaporation of the eluates gives the two products described above. The more polar product is the saturated spirolactone product of the example (17 g); mp. 112° -114° C. Recrystallization from acetone-hexane gives analytically pure material, mp. 121°-122° C. The second product, present in lesser amount, is the less polar 4-(3-oxo-1-indanylidene)-1-piperidinecarboxylic acid ethyl ester described above, mp. 118°-122°; recrystallization from aqueous methanol gives the analytical sample, mp. 114°-116° C.

Provenance & Evidence