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oai:www.ideals.illinois.edu:2142/88173 2023-07-11 col_2142_5131 col_2142_14789 com_2142_5130 com_2142_14788 com_2142_8903

Submission published under a 24 month embargo labeled 'U of I only', the embargo will last until 2017-08-01 The student, Craig Seymour, accepted the attached license on 2015-07-09 at 15:00. The student, Craig Seymour, submitted this Thesis for approval on 2015-07-09 at 15:12. This Thesis was approved for publication on 2015-07-09 at 15:45. DSpace SAF Submission Ingestion Package generated from Vireo submission #8392 on 2015-09-29 at 14:59:17 Made available in DSpace on 2015-09-29T20:49:49Z (GMT). No. of bitstreams: 2 SEYMOUR-THESIS-2015.pdf: 2154904 bytes, checksum: 05d14c29dd5514ca6de800af17d4fa44 (MD5) LICENSE.txt: 4210 bytes, checksum: 2a39146893944454a88b91f5a38e742e (MD5) Previous issue date: 2015-07-09 Embargo set by: Seth Robbins for item 89453 Lift date: 2017-09-29T20:50:34Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system U of I Only Restriction Lifted for Item 89453 on 2017-09-30T09:15:38Z. application/pdf http://hdl.handle.net/2142/88173 en Copyright 2015 Craig H. Seymour thiiranium ion organoaluminum Formation and capture of thiiranium ion intermediates using Lewis acids text text Denmark, Scott E. Seymour, Craig Houghton 2015-09-29T20:49:49Z 2015-09-29T20:49:49Z 2017-09-30T09:15:38Z 2015-08 2015-07-09 The aprotic formation of thiiranium ions and subsequent nucleophilic capture was investigated. It was discovered that β-methoxy and β-acetoxy sulfides could form thiiranium ions in the presences of BF3•OEt2, TMSOTf and various organoaluminum reagents. Treatment of β-methoxy and β-acetoxy sulfides with BF3•OEt2 or TMSOTf allowed for the capture of thiiranium ions by silyl enol ethers, serving as external nucleophiles. However, treatment with Lewis acid caused a drop in the enantiopurity of the thiiranium ion. Varying the amount of Lewis acid, amount and type of nucleophile, temperature and concentration failed to provide conditions where the reaction could proceed in an enantiospecific manner. While investigating new Lewis acids that would allow for enantiospecific formation and capture of thiiranium ions, it was serendipitously discovered that trialkylaluminum reagents could form thiiranium ions and transfer an alkyl group. Further investigation showed that dimethyl(phenylethynyl)aluminum could selectively transfer an alkynyl group. A library of β-acetoxy (2,6-diisopropylphenyl) sulfides was synthesized and underwent both methylation and alkynylation with high yields. It was later determined that the installation of a 2,6-diisopropylphenyl group was unnecessary to achieve high yields and 100% enantiospecificity. A library of various β-acetoxy (phenyl) sulfides underwent methylation and alkynylation with very high yields and 100% enantiospecificity in almost all cases. Arylation and alkenylation via organoaluminum reagents were briefly investigated; however, further studies are needed to successfully prepare the organoaluminum reagent and treat it with β-acetoxy (phenyl) sulfides. 2015-8 Chemistry Chemistry University of Illinois at Urbana-Champaign Thesis M.S.