The Design and Synthesis of Chiral Sulfides for Use in Asymmetric Epoxidations

This thesis describes the design and synthesis of chiral sulfides for use in asymmetric cpoxidations. Chiral sulfides have been designed around the naturally-occurring chiral starting materials carvone and 'limonene. This has enabled the synthesis of new chiral sulfides as single enantiomers without the need for any resolution to be performed. Carvone-based sulfides 43 and 53 have been synthesised and can be used to produce cpoxides in high selectivity. The synthesis of racemic chiral sulfides has also been investigated and conditions have been developed for the addition 'of non-nucleophilic heterocycles to bicyclic sulfide 76. These conditions have been used with a range of heterocycles that are unreactive towards addition to 76 via existing conditions. C2-symmetric sulfides 81, 82, 86, and 87 have been synthesised but were found to be unreactive towards alkylation. The addition of sulfenyl chlorides to alkenes has also been investigated as a method for synthesising chiral sulfides from chiral naturally-occurring alkenes. Epoxidations using ylides ,stabilised by anionic amide groups have also been researc~ed. Chiral sulfonium salt 67 has been synthesised, but failed to produce epoxides in high enantioselectivities.EThOS - Electronic Theses Online ServiceGBUnited Kingdo