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Title: Lithiation-borylation methodology : application to the synthesis of α-Heterocyclic tertiary alcohols, adjacent quaternary stereocenters and tetrasubstituted alkenes
Author: Watson, Charlotte G.
ISNI:       0000 0004 5917 3416
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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The use of nitrogen containing heterocyclic boronic esters in the lithiation-borylation reaction was investigated; a range of pyridyl boronic esters were utilised, and it was found that not only could the α-heterocyclic tertiary alcohols be generated, but also I-pyridyl-l-arylethanes could also be accessed by protodeboronation of the intermediate tertiary boronic esters. This work focuses on the use of highly electrophilic dimethylboranes to effect iterative homologations with secondary benzylic carbamates to create tertiary alcohols or C-tertiary amides with an adjacent quaternary stereo center. The reaction has a reasonable scope, and stereocontrol at each quaternary center is extremely high, giving the double homologation products in excellent enantio- and diastereoselectivity. In addition to the homologation methodology, a method to aminate the tertiary dimethylborane products was developed. A new process was developed that allows for the synthesis oftetrasubstituted alkenes with high stereo control. Lithiation-borylation of secondary benzylic carbamates with trisubstituted vinylic boronic esters gives α,α-disubstituted allylic tertiary boronic esters, which undergo allylboration to give homoallylic alcohols with full control over two stereogenic centres and complete olefin selectivity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available