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Title: Studies of the reactions of nucleophilic organophosphorus species with organic cabonyl-coataining compounds
Author: Cheong, Yuen-Ki
ISNI:       0000 0004 2745 263X
Awarding Body: University of London
Current Institution: Queen Mary, University of London
Date of Award: 2007
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The majority of this project is to discover novel mechanistic pathways for a wide range of organic reactions involving different carbonyl compounds with trivalent phosphorus compounds. The first part of our research involved the one-pot intra-molecular cyclisation reaction of the different 2-substituted benzoylphosphonates in the presence of triniethyl phosphite. The mechanistic pathway of these reactions was found to intra-molecular insert to the electrophilic carbonyl centre in the substituent via the initially formed carbanionic intermediate. The subsequently formed tricyclic phospholane intermediate [δp ~ -48 (d) & +18 (d), Jpp 33 Hz] were observed from the NMR spectra of the crude reaction prior the "formation of the final cyclic benzofuranyl-phosphonate products. Experiments were carried out ,to study the decomposition product of the observed phospholane intermediate in the absence of phosphite, which led to. the formation of the novel ~- ketophosphonates. We have also generated a senes of anionic intermediates in situ usmg different phosphate- phosphonates, and studied their anionic manors inter- and intra- molecularly toward the electrophilic carbonyl reacting sites. The second part of our project involved the reactions of various halogeno-substituted 2,5-cyclic- diones with different trivalent phosphorus compounds. Under the treatment of trialkyl phosphites, many of the, related non-halogenated substituted cyclic diones were report to process deoxygenations reaction followed .by dimerisations and .rearrangements reactions. , However, in Our practical, a range of unusual stabilised phosphonium ylides were isolated and their structures were studied analytically in. detail by the NMR data. In particular, .ylidic phosphinie oxide and ylidic bisphosphine oxide were successfully crystallised, which allowed us to study the physical properties of these ylides by the X-ray crystallography. The mechanistic pathways of these reactions proceeded differently, depending on the number of substituents on the cyclic diones.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available