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Title: Applications of the lithiation/borylation methodology : diastereoselective homologation of tertiary boronic esters for the construction of a-substituted allylic boronic esters and subsequent E-selective allylboration
Author: Scott, Helen Kathleen
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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The asymmetric construction of quaternary stereocenters is a significant synthetic challenge due to the high steric repulsion between the carbon substituents that is generated upon their construction. However, tertiary boronic esters have been found to be suitable precursors. In addition, the construction of a second stereo genic centre adjacent to the newly formed quaternary centre has been achieved. Reaction of teliiary boronic esters 38 with simple (chloroallyl)lithiums, generated in situ at low temperature, affords the secondary allylic boronic esters 182 bearing an a-quaternary stereocenter in high yields and excellent dr and er. The scope of this reaction is restricted by the steric nature of the R substituent on the boronic ester. The exceptional levels of diastereoselectivity have been discussed with reference to the reactivity-selectivity principle.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available