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Title: Investigations of the coupling reactions of organoborates
Author: Williamson, H. M.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1986
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The inclusion in a borane of a 2-amino alkoxy group confers borate character to the borane. The susceptibility of some such aryl and heteroaryl borates to undergo electrophilically induced 1,2-intramolecular rearrangement and coupling was studied. High yields of coupled biaryls were obtained from borates including a thienyl moiety; moderate yields were obtained from borates including a furyl group. An unsubstituted phenyl group was found not susceptible to electrophilic attack. Borates including substituted aryl groups were found to be very susceptible to electrophilic α-attack. The borate salts showed remarkable specificity of reagent as only bromine as an electrophile was useful to initiate rearrangement. With other reagents, products of electrophilic α-attack and borate decomposition without coupling were detected. Attempts to induce coupling by chemical oxidation and photochemical means were unsuccessful. The usefulness of some dialkoxyborates as precursors to coupled biaryls and diacetylenes was studied. Moderate yields of coupled products were obtained. From a borate including two 2-thienyl groups, the product 5,5'-dibromo-2,2'-bithiophene was obtained in high yield by appropriate selection of reaction conditions. Treatment of 3-hydroxydecanoic acid with tris(ethylthio)borane allows 3-hydroxy S-ethyl decanethioate to be obtained in good conversion. No similar reaction was found when tris(thiophenyl)borane was used.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available