stallizes as long needles: mp 38-39°; [a] 2Sd +72°(c 1.0, chloroform); yield 1.14 g (40%).Photolysis of 3-azido-3-deoxy-1,2:5,6-di-O-isopropylidene-a-Dallofuranose.-The above azide (4.85 g) in 1 1. of benzene was irradiated 18 hr after which the solution was concentrated and refluxed with aqueous ether (50 ml). After concentrating to dryness, the syrup was applied to a silica gel column and eluted with chloroform-acetone (15:1 v/v). Progress was followed by tic and the fraction containing the ketone hydrate crystallized from ether-hexane: mp 113-114°; [a] 85d +45°(c 1.0, chloroform); yield 1.6 g (34%). Rt and ir values and mixture melting point were identical with those of an authentic sample. Elemental analysis agreed with calculated values.Registry No.-3-Azido-3-deoxy-l, 2:5,6-di-O-isopropylidene-ct-D-allofuranonse, 21870-78-0.

the layers were separated. The aqueous layer was neutralized with sodium bicarbonate and extracted with three 50-mi portions of ether. The combined ether extracts were concentrated at reduced pressure on the steam bath.18 If the residue contained a mixture of solid and an oil, it was washed with 10 ml of cold (0°) methanol and filtered immediately. If a solid was not (18) Conveniently, crystallization was found to be hastened if the ether extracts were not dried before removal of excess solvents, especially when p-methoxyaryl isoxazoles were synthesized.Kovacs, Mayers, Johnson, Cover, and Ghatak formed, 5-10 ml of methanol was added and crystallization occurred upon refrigeration of the mixture. Recrystallization was effected with ethanol or benzene (see Table I).

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The acid-catalysed decomposition of ethyl diazoacetate has been studied in the presence of sodium perchlorate, potassium chloride, potassium bromide, and potassium iodide. With halide ions some of the product is ethyl halogenoacetate rather than ethyl glycollate. The overall kinetics a n d product ratios have been measured and it has been shown that the halide ions take part in the rate-determining step which leads to halogenoacetate. The rate constants for this process for chloride, bromide, and iodide ions give a linear Swain-Scott nucleophilicity plot, but the rate constant for water is smaller than expected, which suggests that there is no change in mechanism and that it participates as a nucleophile in the glycollate reaction.