ORGN 511 |
| Hydrozirconation of alkynes, utilizing Schwartz's reagent, {Cp2Zr(H)Cl}, is a superb protocol for making regioselective vinylzirconocene reagents. Although organozirconocenes have been used in many applications for organic synthesis, the transmetallation from zirconium to zinc has been demonstrated to be a more efficient subsequent procedure in the synthesis of carbon-carbon bonds. The reaction of the vinylzincate to benzalacetone utilizing the CuI•0.75DMS (DMS = dimethyl sulfide) complex gave the 1,4-product in 94% illustrates the efficiency of the Cu(I) catalyst. The 1,2-addition product is avoided and the reaction rate is faster than the corresponding vinylzirconocene. The catalytic efficiency of the CuI•0.75DMS complex is most efficient when compared to various other copper(I) and copper(II) sources as well as Ni(acac)2. The conjugate addition of alkenyl-alkylzinc reagents to N-enoyl derived oxazolidinones was also investigated. Interestingly, employing TMSOTf as a Lewis acid achieved high yields of the desired b-substituted N-enoyl oxazolidinones, and only 10 mol% of the CuI•0.75DMS catalyst was applied.
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New Reactions and Methodology, Heterocycles and Aromatics, Bioorganic Chemistry
8:00 PM-10:00 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster
Sci-Mix
Division of Organic Chemistry |
