2026-09-21T14:06:14Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/19549 2023-07-10 col_2142_5131 col_2142_14789 com_2142_5130 com_2142_14788 com_2142_8903

Denmark, Scott E. Forbes, David Christopher 2011-05-07T12:11:06Z 2011-05-07T12:11:06Z 10000-01-01 1996 A practical, general and efficient protocol for the catalytic epoxidation of alkenes has been developed. The in situ generation of reactive dioxiranes capable of epoxidizing a variety of alkenes under biphasic conditions has been accomplished using phase transfer catalysts bearing a carbonyl group. Optimal epoxidation conditions employ 10 mol % of 1-dodecyl-1-methyl-4-oxopiperidinium trifluoromethanesulfonate (9d$\sp+$OTf$\sp-)$ in a $\rm CH\sb2Cl\sb2$/pH $7.5{-}8.0$ biphase using potassium monoperoxosulfate (Oxone) as the oxidant. Optimization of the conditions identified (1) slow addition rate, (2) pH 7.5-8.0, (3) n-dodecyl chain, and (4) the triflate salt as key experimental and structural variables. Efforts to develop an asymmetric epoxidation of alkene protocol using chiral, non-racemic ketone promoters are also reported. Chlorodifluoroketone promoter 36 was synthesized in 13 steps and subjected to our standard epoxidation of alkenes system and resulted in complete conversion when the reaction solution was emulsified and a level of asymmetric induction of 14% ee. Also described is a stereochemical study on the intramolecular hydrosilylation of $\alpha,\beta$-unsaturated esters. The intramolecular hydrosilylation of several 3-methyl-4-siloxy-2-butenoates afforded cis-disubstituted $\gamma$-lactones after desilylation. The diastereoinduction was sensitive to the bulk of the allylic substituents, but not to the groups on silicon. The origin of asymmetric induction is believed to be the A$\sp{1,2}$ strain from the $\beta$-methyl group. Made available in DSpace on 2011-05-07T12:11:06Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9702514.pdf: 10992081 bytes, checksum: f33508f4ec3da65394ec3773cb111d61 (MD5) Previous issue date: 1996 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:37:47Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:15:36-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only 9780591087567 AAI9702514 (UMI)AAI9702514 http://hdl.handle.net/2142/19549 eng Copyright 1996 Forbes, David Christopher Chemistry, Organic Dioxirane-mediated epoxidation of alkenes: The development of catalytic and asymmetric protocols text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.