http://hdl.handle.net/10339/30044 2013-05-19T17:40:16Z 2013-05-19T17:40:16Z Junker, Christopher S. Welker, Mark E. http://hdl.handle.net/10339/37157 2012-05-17T16:38:06Z 2012-01-01T00:00:00Z

Ruthenium Carbenes as Catalysts in stereoselective ene-yne Metathesis/Diels-Alder and ene-yne Metathesis/Diels-Alder/Cross coupling multicomponent reactions Junker, Christopher S.; Welker, Mark E. An ene-yne cross metathesis of silyl substituted alkynes and alkenes followed by a Diels-Alder reaction of the metathesis product 2-silyl-1,3-dienes has been developed. The dienes thus prepared in situ were shown to participate in highly diastereoselective Diels-Alder reactions. In one case the silicon substituted Diels-Alder cycloadduct was subsequently used without isolation and purification in a Hiyama cross coupling reaction. The cross coupling reactions enable these silicon dienes to be used as synthons for a variety of other dienes.

2012-01-01T00:00:00Z Pietsch, E. Christine Hurley, Allison L. Scott, Elizabeth E. Duckworth, Benjamin P. Welker, Mark E. Leone-Kabler, Sandra Townsend, Alan J. Torti, Frank M. Torti, Suzy V. http://hdl.handle.net/10339/36134 2011-08-29T21:05:30Z 2003-01-01T00:00:00Z

Oxathiolene oxides: a novel family of compounds that induce ferritin, glutathione S-transferase, and other proteins of the phase II response Pietsch, E. Christine; Hurley, Allison L.; Scott, Elizabeth E.; Duckworth, Benjamin P.; Welker, Mark E.; Leone-Kabler, Sandra; Townsend, Alan J.; Torti, Frank M.; Torti, Suzy V. Compounds that induce the synthesis of cytoprotective phase II enzymes have shown promise as cancer chemopreventive agents. Although chemically diverse, phase II enzyme inducers are capable of participating in Michael reaction chemistry. We have synthesized a novel class of organosulfur compounds, termed oxathiolene oxides (OTEOs). Based on their chemical properties, we hypothesized that these compounds could function as phase II enzyme inducers. Northern blot analysis showed that oxathiolene oxides induce the phase II enzymes glutathione S-transferase (GST), NAD(P)H:quinone oxidoreductase 1 (NQO1), and ferritin H and L mRNA in a concentration-dependent fashion in a normal embryonic mouse liver cell line, BNLCL.2. OTEO-562 (3-cyclohexenyl-4-methyl-1,2-oxathiol-3-ene-2-oxide) was the strongest inducer. Western blot analysis demonstrated that GST-α and ferritin H protein levels were also induced in cells treated with OTEO-562, as was total GST and NQO1 enzyme activity. Further, induction of NQO1 activity by OTEO-562 was equivalent in aromatic hydrocarbon (Ah) receptor wild-type and Ah receptor mutant cell lines, suggesting that oxathiolene oxides activate phase II enzymes by an Ah receptor-independent mechanism. Consistent with this observation, OTEO-562 failed to induce cytochrome P450 1A1 mRNA. These results suggest that oxathiolene oxides may merit further investigation as candidate chemopreventive agents.

2003-01-01T00:00:00Z Pickin, Kerry A. Day, Cynthia S. Wright, Marcus W. Welker, Mark E. http://hdl.handle.net/10339/36131 2011-08-29T21:05:50Z 2003-01-01T00:00:00Z

A Cobaloxime Substituted Terminal Alkene Which Rapidly Isomerizes to a Cobaloxime Substituted Internal Alkene Complex Pickin, Kerry A.; Day, Cynthia S.; Wright, Marcus W.; Welker, Mark E. An unusual cobaloxime substituted terminal alkene has been isolated and characterized by X-ray crystallography. The double bond in the alkene readily isomerizes but the title compound could be isolated and structurally characterized at low temperature.

2003-01-01T00:00:00Z Crook, Kenneth E. Nie, Jin Welker, Mark E. http://hdl.handle.net/10339/36130 2011-08-29T21:06:56Z 2008-01-01T00:00:00Z

Substituted Dienols from Palladium Catalyzed Coupling of Hydroaluminated Enynols with Aryl Iodides Crook, Kenneth E.; Nie, Jin; Welker, Mark E. Enynols were hydroaluminated and cross coupled with aryl iodides. Reduction of the yne portion of the enynol is a serious side reaction so reaction conditions to minimize reduction and maximize cross coupling were investigated in detail.

2008-01-01T00:00:00Z