Optical Activity of Open Chain Compounds 5475 violet, but showing bands in the infrared at 6.05 and 11.2 µ in chloroform solution typical of an exomethylene function. Elution of the column with benzene afforded the cyclopropyl ketone V (see below) followed by mixtures of the cyclopropyl ketone V14 and the 16-methyl-±16-20-ketone III.14Reaction of the Exomethylene Ketone IV with Potassium Hydroxide.-A solution of 10 mg. of IV in 15 ml. of 5% potassium hydroxide in methanol was refluxed for 2 hours. The solvent was removed in vacuo, the residue triturated with water and the crystalline product, after recrystallization from acetone, was identical in all respects with an authentic sample of 3a-hydroxy-16-methyl-16-pregnene-ll,20-dione.Reaction of the Exomethylene Ketone IV with Osmium
It is postulated that reductions at metal surfaces occur with the formation of resonance-stabilized chemisorption complexes as intermediates. It is suggested that a hydrogen chemisorption complex is the active reducing agent at electrodes of low hydrogen overvoltage and in catalytic hydrogenation (indirect reduction). Reduction at electrodes of high hydrogen overvoltage or by means of active metals appear to involve organic chemisorption complexes as key intermediates (direct reduction). Detailed ionic mechanisms for the direct and indirect reduction of ketones are presented.
A new antibiotic, streptimidone (CieHssNCh), has been obtained from the culture filtrates of a Streptomyces. The chame teristic physical properties of the antibiotic have been determined. Degradative studies have demonstrated that streptimidone is 3-(2-hydroxy-7-methyl-5-methylene-4-oxo-6-nonenyl)-glutarimide. A novel cross-conjugated chromophore is proposed for the dienone.
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