Azabicyclo[3.3.0]octenones and azabicyclo[4.3.0] nonenones have been obtained by cyclisation of hexacarbonyldicobalt complexes of aza-heptenynes and -0ctenynes respectively. A n unusual feature of the cyclisation of N-acyl-4-azahept-1 -en-6-ynes is the extensive formation of the reduced products, N-acyl -3-aza bicyclo [ 3.3.01 octan -7 -ones under most reaction conditions.The first example of an intramolecular Khand reaction was the formation of the 2-oxabicylononenone (1) from the cobalt complex of pent-4-ynyl vinyl ether. Numerous 3-oxabicyclo-[3.3.3]oct-5-en-7-ones[ 5-oxa-4,5,6,6a-tetrahydro-1 H-pentalen-2-ones] have subsequently been efficiently synthesised in the same way from variously substituted ally1 prop-2-ynyl ether^.^-^
Abstract. The oxidation of the sulfide group in penicillin G potassium salt to the sulfoxide with hydrogen peroxide has been investigated using a wide range of polyoxometalates immobilized on high-surface-area supports. The highest activity and selectivity for the sulfur oxidation of the penicillin compound was obtained with ammonium molybdate supported on to strongly basic anion-exchange resin. The oxidation proceeds smoothly at ambient and sub-ambient temperatures in water or water/alcohol solvents. The use of supported oxidation catalysts has been extended to the transformation of benzenethiol to benzenesulfonic acid which was found to proceed in high yield and selectivity employing phosphotungstic acid on y-alumina. The use of a supported catalyst with H ,02 as the primary oxidant allows the circumvention of environmental and product isolation problems to be overcome simply and economically.
The target compounds (IV) and (VI) are obtained from the Co complexes of (III) and (V) under various conditions (photochemical, ultrasonic and thermal).
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