Haji-Cheteh, Chehasnah (2016) Synthesis of phosphine-alkene ligands and 3-hydroxy piperidines using organolithium chemistry. PhD thesis, University of York.
Abstract
This thesis describes synthetic routes to P-stereogenic phosphine-alkene ligands and 3-hydroxy piperidines containing heteroaromatics via lithiation-trapping of phosphine boranes or N-Boc pyrrolidine. Both topics are introduced in chapter 1.Chapter 2 presents a route to a new type of P-stereogenic phosphine-alkene ligand B prepared by racemic lithiation of t-butyldimethylphosphine borane or dimethylphenylphosphine borane using s-BuLi. Different allylic halides were used to trap the lithiated intermediate to give chiral alkene-phosphine boranes A. In chapter 3, 3-hydroxy piperidines were synthesised from the ring expansion of hydroxy pyrrolidines. Two novel, short and simple synthetic routes were developed (as shown below). Lithiation-trapping reaction of N-Boc pyrrolidine C using pyridine carboxaldehydes gave N-Boc pyrrolidine alcohols syn-D and anti-D. On the other hand, an alternative approach to obtain 3-hydroxy piperidines anti-H starting from N-trityl prolinal E derived from (S)-proline was investigated. Addition of lithiated heteroaromatics, generated from a Br/Li exchange reaction, to N-trityl prolinal E diastereoselectively gave N-trityl alcohols anti-F. The Boc or trityl deprotection and reductive amination then gave N-benzyl pyrrolidines syn-G and anti-G. Finally, the ring expansion via an aziridinium ion of alcohols syn-G and anti-G gave 3-hydroxy piperidines syn-H and anti-H. The stereochemistry of 3-hydroxy piperidines syn-H and anti-H was proven using J-values in the 1H NMR spectra.
Metadata
Supervisors: | O'Brien, Peter and Fairlamb, Ian |
---|---|
Related URLs: | |
Awarding institution: | University of York |
Academic Units: | The University of York > Chemistry (York) |
Identification Number/EthosID: | uk.bl.ethos.693260 |
Depositing User: | Miss Chehasnah Haji-Cheteh |
Date Deposited: | 08 Sep 2016 09:56 |
Last Modified: | 19 Feb 2020 13:03 |
Open Archives Initiative ID (OAI ID): | oai:etheses.whiterose.ac.uk:13889 |
Download
Filename: PhD thesis_Chehasnah Haji-Cheteh.pdf
Description: PDF
Licence:
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 2.5 License
Export
Statistics
You do not need to contact us to get a copy of this thesis. Please use the 'Download' link(s) above to get a copy.
You can contact us about this thesis. If you need to make a general enquiry, please see the Contact us page.