Synthetic studies of 3-deoxy-D-manno-2-octulosonic acid (KDO), 3-deoxy-D-arabino-2-heptulosonic acid (DAH), and their 4-epimers through the radical chemistry of Barton esters /
The radical chemistry of thiohydroxamates (Barton esters) was
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739891171&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The radical chemistry of thiohydroxamates (Barton esters) was applied to the synthesis of the higher monosaccharides 3- deoxy-D-manno-2-octulosonic acid (KDO), 3-deoxy-D-arabino-2- heptulosonic acid (DAH), and their 4-epimers starting from commercial D-glucono-1,5-lactone and D-ribonolactone, respectively. DAH was synthesized in a concise manner and with good diastereoselectivity, for the first time, by radical chemistry. The regeneration of the carbonyl group from phenylhydrazones by oxidation with hypervalent organoiodine reagents, benzeneseleninic anhydride (BSA), and nickel peroxide was studied. a-Acetoxy and a-alkyloxy azo compounds were synthesized by the oxidation of hydrazones with hypervalent organoiodine reagents. From the oxidation of 2-phenylhydrazono-,v-butyrolactone, a novel rearrangement leading to hexahydro1,3-oxazine-2,4-dione derivatives was discovered. The synthetic utility and radical mechanisms of the oxidation of phenylhydrazones with BSA and nickel peroxide were established. Numerous methods for the conversion of N',Ndimethylhydrazides to carboxylicacids were developed. 2-Mercaptopyridine and thiophenol were used to manipulate the 2- and 3-positions of propionate esters. Acrylamide proved to be an effective radical trap for carbon radicals generated from Barton esters. By this radical chemistry, homologation of carboxylic acids to primary carboxamides and the synthesis of mesoionic compounds, namely the anhydro-2-alkyl3-acyliminothiazolo[3,2-a]pyridinium hydroxide derivatives, were achieved. |
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| Item Description: | Vita. "Major Subject: Chemistry". In title, numerals are used. |
| Physical Description: | ix, 222 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 203-219. |