Synthesis of bicyclics using vinylboranes /
A concise synthesis of decalin using the first example of the
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=736584521&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | A concise synthesis of decalin using the first example of the intramolecular DielsAlder reaction of vinylboranes is described. The essential triene precursors 33, 349 36 and 37 are readily available from the versatile Gassman one-pot triene synthesis. The air-sensitive 1,7,9-decatrienylboranes 39 and 50 were generated in situ from either hydroboration of 37 with dicyclohexylborane or boron-tin exchange of 33 with Br-9BBN. The intramolecular Diels-Alder reactions of 39 and 50 were found to be highly stereoselective. A systematic synthetic, kinetic, and theoretical study of intramolecular DielsAlder reactions of vinylboranes was carried out. Stereoselective syntheses of the precursor tributylstannyltrienes are described. The intramolecular Diels-Alder reactions of trienylboranes 116 and 118-122 are highly stereoselective. The corresponding theoretical studies of the reactions, for the first time, established the presence of twist asynchronicity strain in the intramolecular Diels-Alder reactions and also accurately predicted the ratio of endo/exo products distribution in the reaction of 117. The twist asynchronicity strain was estimated to be about 3 kcal/mol. A concise, versatile synthesis of bridgehead alcohol bicyclics using the powerful neutral dienophiles- cycloalkenyldibromoboranes 203 and 204 is also described. The Diels-Alder reactions of the cycloalkenylboranes were found to be highly meta and endoselective in the reactions of various dienes. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xvi, 285 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 183-188. |