Miscellaneous Oxidation Processes

Other methodologies can be appUed for the direct enantioselective organocata-lytic a-oxidation of carbonyl compounds [146]. Thus, proline (21), pyrrolidinyl tetrazole (36), or its a-methyl derivative (30mol%) catalyzed the oxidation of several aldehydes and cyclohexanone using tron.s-2-(p-methoxyphenylsulfonyl)-3-phenyloxaziridine as oxidant [147], with the use of a-methyl substituted derivatives affording the a-oxidized aldehydes with moderate results (23-67% yield, 12-45% ee). 

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In miscellaneous oxidative processes of indoles, two methods for the preparation of 3-hydroxyindoles have been reported. The first approach involves initial Vilsmeier-Haack reaction of indole-2-carboxylates 176 to afford the corresponding 3-formyl analogs 177. Activation of the aldehyde with p-toluenesulfonic acid (PTSA) and Baeyer-Villiger oxidation with m-chloroperoxybenzoic acid (wi-CPBA) then affords high yields of the 3-hydroxy compounds 178 <00TL8217>... 

For other reports of acetals, see the section titled Miscellaneous Oxidative Processes later. 

Miscellaneous ring closure reactions involving carbon-carbon bond formation are shown in Scheme 72 and 73. An oxidation-cyclization-oxidation process was effected by PCC to convert alcohols 197 to 4-piperidones 198 <04JOC3226>. Intramolecular alkylation was used to covert chiral enaminone 199 to 200, a key intermediate in the total synthesis of lepadin alkaloids... 

A hst of 74 GLS reacdions with hterature references has been compiled by Shah Gas-Liquid-Solid Reactions, McGraw-HiU, 1979), classified into groups where the solid is a reactant, or a catalyst, or inert. A hst of 75 reactions made by Ramachandran and Chaudhari (Three-Phase Chemical Reactors, Gordon and Breach, 1983) identifies reactor types, catalysts, temperature, and pressure. They classify the processes according to hydrogenation of fatty oils, hydrodesulfurization, Fischer-Tropsch reactions, and miscellaneous hydrogenations and oxidations. 

Cadmium, as cadmium oxide, is obtained mainly as a by-product during the processing of zinc-bearing ores and also from the refining of lead and copper from sulfide ores (USPHS 1993). In 1989, the United States produced 1.4 million kg of cadmium (usually 0.6 to 1.8 million kg) and imported an additional 2.7 million kg (usually 1.8 to 3.2 million kg). Cadmium is used mainly for the production of nickel-cadmium batteries (35%), in metal plating (30%), and for the manufacture of pigments (15%), plastics and synthetics (10%), and alloys and miscellaneous uses (10%) (USPHS 1993). 

Miscellaneous sulfur-containing reagents. Culvenor ami cn workers8 1 were the first to examine briefly the action of alkaline potassium thiosulfate on ethylene oxide. The products isolated by Uh-jm were potassium isethionato (potassium 0-hydroxyethanesulfonnte enrl -hydroxyethane sulfuuc add. The course postulated fear this process was as shown in Eq. (696). 

Besides processes (1) and (2), the reader should be aware that nucleophilic attacks on alkynes are treated in other chapters of this book, dealing with rearrangements, cyclizations, polyacetylenes, cyclic acetylenes and perhaps others. A number of publications overlap with ours in different ways and at different levels -. They treat individual alkynes or families " , e.g. acetylene, diacetylenes , acetylene dicarboxylic esters haloacetylenes , alkynyl ethers and thioethers > ynamines , fluoro-alkynes ethynyl ketpnes , nitroalkynes , etc. synthetic targets, e.g. pyrazoles , if-l,2,3-triazoles , isothiazoles , indolizines S etc. reagents, e.g. nitrones , lithium aluminium hydride , heterocyclic A -oxides - , azomethine ylids - , tertiary phosphorus compounds , miscellaneous dipolar nucleophiles - , etc. The reader will appreciate that all of these constitute alternate entries into our subject. 

The different applications have been classified by reaction type oxidation (sect. 2.1-2.3), hydrogenation (sect. 2.4), environmental (sect. 2.5) and miscellaneous (sect. 2.6). The environmental applications have been grouped together in view of the present relevance of this field. It includes total oxidation of organic compounds and CO, redox processes such as CO+NO reaction and NO/N2O decomposition. 

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