No abstract

A solution of o-anisidine and ethyl oxaloacetate in ether was refluxed in a Soxhlet extractor using calcium hydride in the extraction thimble, so that the hydride continuously removed the water produced by anil formation. For comparative yields, a preparation of ethyl oxaloacetate (synthesized from ethyl acetate and ethyl oxalate) was divided into two parts, and one part run as originally described1 2 (refluxing benzene over Na2S04) and one part as described above. Cyclization of the anils without isolation gave yields of 20% and 50%, respectively, of the ester, II, based on ethyl acetate.It was found that hydrolysis of the ester, II, did not take place effectively, at least on this small scale, using the proportions of potassium iodide and 95% phosphoric acid recommended.2 However, by increasing the relative amount of phosphoric acid, a nearly quantitative yield of xanthurenic acid was obtained from II.EXPERIMENTAL Preparation of ethyl oxaloacetate-4-Cli. Ethyl acetate-1-C14, prepared in approximately 86% yield from 588 mg. (7.17 mM., 4.8 me.) of sodium acetate-l-C14 essentially by the method of Ropp,3 was mixed with 0.825 ml. of diethyl oxalate in 2 ml. of dry ether. This solution was added dropwise with stirring to a cooled (ice bath) suspension of sodium ethoxide (from 153 mg. of sodium hydride and 0.356 ml. of absolute ethanol) in 2 ml. of dry ether. The mixture was stirred in the cold for 2 hr. and then allowed to stand overnight at room temperature. The resulting grey paste