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Title: Studies on new mono- and di-lithiated complexes of organic molecules
Author: Ball, S. C.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 1997
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This thesis describes the syntheses and characterisations of new mono- and di-lithiated complexes of organic molecules of the general formula [(Rx-).xLi+].yL. The anion Rx- is either derived from a primary amine or is from a multifunctional organic molecule, containing one or more heteroatoms (usually N or S). The complexes have been prepared either by direct reaction of a simple amine with a metal source (solutions of nBuLi, tBuLi, LDA), or via a multi-stage reaction following an established synthetic organic protocol, attempt to isolate the lithiated intermediates at each stage. A variety of solvents, both hydrocarbon (toluene, hexane) and polar solvents (diethylether, THF), were used and all of the metallated complexes contain stoichiometric quantities of Lewis base donors, L (TMEDA, PMDETA, THF, Et2O). One mono-sodiated complex is also described. The work presented concentrates on the preparation and characterisation of new dilithiated complexes both in the solid state and in solution. The lithiated intermediates in many organic reactions provide a source of such dilithiated molecules. In general deprotonation of an organic acid, followed by insertion of a functional group (CS2, RCN) into the E-M bond (E=C, N; M=Li, Na) and in some cases further metallation, forms the basis of the reactions described. Chapter 1 provides a general introduction to the area of lithiated organics, with a brief review of X-ray structure analyses and solution studies on such complexes. In Chapter 2 the general experimental methods used to synthesise and characterise these complexes are described. Chapter 3 reports an investigation into an established synthetic protocol for the conversion of β-substituted N-containing heterocycles to their pyrrolo derivatives via metallation and nitrile insertion. Details of complexes 3-C5H4NCH=C(Ph)NHC(Ph)=NLi.PMDETA and 2,3-C5H4NCH=C(R)NX.xTHF ("problem") are provided where R=Ph or tBu and X=Li (L=THF) or X=H. The preparation and characterisation of the mono- and di-lithiated complexes of the related α-substituted pyridine derivatives are also described.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available