Synthesis studies to single stereoisomers of the vicinal trifluoroalkane motif

Organofluorine compounds--Synthesis;Stereoisomers

Brunet, Vincent A. ; O'Hagan, David ; O'Hagan, David

University:University of St Andrews

Department:Chemistry (School of)

关键词: Organofluorine compounds--Synthesis;    Stereoisomers;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/853/VincentBrunetPhDThesis.pdf?sequence=3&isAllowed=y

来源: DR-NTU

【 摘 要 】

This thesis focuses on the construction of individual isomers of the R-CHF-CHF-CHF-R’motif. The multi-vicinal fluorine motif is new in organic chemistry and thereforestereoselective methods giving rapid access to these motifs and with flexibility need to beexplored. The research in the thesis succeeded in the preparation of (2S,3R,4S)-314 and(2S,3S,4R)-328.In Chapter 1, an overview of the impact of fluorine in organic molecules is given. Recentdevelopments in asymmetric electrophilic and nucleophilic fluorination are described, as wellas the preparation of multivicinal fluoroalkane motifs.Aldol reactions of either (R)- or (S)-N-(α-fluoropropyl)-2-oxazolidinones, mediated by TiCl 4are reported in Chapter 2. Such aldol reactions gave rise to identical α-fluoro-β-hydroxy-aldol products with high diastereoselectivities (95% dr). After removal from the auxiliary α-fluoro-β-hydroxy- products were converted to the corresponding α,β-difluoro products.The synthesis of non symmetric vicinal trifluoro motifs (2S,3R,4S)-314 and (2S,3S,4R)-328 isdescribed in Chapter 3. They were prepared by direct fluorination in three steps of thecorresponding (2R,3R,4R)-erythro and (2R,3S,4S)-threo enantio-enriched epoxy-alcohols. Thetwo erythro and threo epoxy-alcohol isomers behave very differently during the firstfluorination step and then an attempt to study and rationalise this difference in behaviour ismade.