Ethyl acetate, III

Indanedioiie (III) may also be prepared by condensation of diethyl phthalate (V) with ethyl acetate in the presence of sodium ethoxide the resulting sodium 1 3-indanedione-2-carboxylic ester (VI) upon warming with sulphuric acid yields (HI). 

A solution of 5 g (14 mmoles) of 5a-cholest-2-ene in 100 ml ethyl acetate and 8 ml of 2.8 M (22 mmoles) cyanogen azide (CAUTION See Chapter 15 and ref. 139b) in ethyl acetate is heated at 50-53° for 24 hr, during which time about 22 mmoles of nitrogen is evolved. Solvent is removed by evaporation and the residue is applied in benzene to a column of 160 g of neutral alumina (activity grade III). Elution with petroleum ether-benzene (1 1) gives 1.6 g of... 

A solution of 500 mg 3 -acetoxypregn-5-en-20-one-[17a,16a-c]-A -pyrazoline in 100 ml of anhydrous dioxane is stirred with a magnetic stirrer and irradiated in a water-cooled quartz reactor with a high pressure Biosol Philips 250 W quartz lamp for 1 hr. The solvent is removed at reduced pressure and the residue is chromatographed on alumina (activity III). Elution with petroleum ether-benzene (3 1) gives 0.2 g (42%) of 3 -acetoxy-16a,17a-methylene-pregn-5-en-20-one mp 193-193.5° after two recrystallizations from methylene dichloride-ethyl acetate. 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

A 4 g 3-indoleacetic acid (I) in ether. I reat with PCi5 as described elsewhere here to get 2.7 g of the chloride (II). Dissolve 2.7 g (II) in 40 ml ethyl acetate and add 2 ml piperidine (or equimolar amount other amine), 3.5 ml N-ethyl-piperidine in 40 ml ethyl acetate. Let stand three hours at room temperature and filter. Wash filtrate with IN HCI, 10% Na carbonate and evaporate in vacuum to get 1 g of the amide (III) (test for activity). Add 1 g (111) in 25 ml ether to 1.4 g lithium aluminum hydride in 50 ml ether stir four hours at room temperature and reflux one-half hour. Cool and carefully add water until no more bubbling. Add 3 ml 20% NaOH and dry. evaporate in vacuum to get 1 g piperidine analog of DMT... 

Solvent systems are I=heptane - 2 runs, II=benzene-ethyl acetate (3 1)-2 runs, III=butanol-acetic acid-water (6 1 1), IV=chloroform-methanol (9 1). 

Among the Bi(III) salts screened, Bi(OTf)3-xH20 was the most efficient catalyst, and the best solvent was found to be CH2Cl2. When the reaction was performed using ethyl acetate as the solvent, betulin-28-yl acetate was obtained as the major reaction product, which demonstrated that Bi(0Tf)3-xH20 is also an interesting transesterification catalyst (Scheme 38). 

Table III. Homologation of Methyl Acetate to Ethyl Acetate Effect of Iodide Source...

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