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Columbia Dissertations and Theses > Doctoral Dissertations
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| Author(s): | Krauss, Isaac |
| Title: | Highly regioselective diastereoselective directed hydroformylation of allyl ethers ; Highly practical and enantioselective ligands for Cu-catalyzed conjugate addition |
| Physical Description: | iv, 115 leaves, bound. |
| Issue Date: | 2003 |
| Description: | Department: Chemistry. Thesis (Ph. D.)--Columbia University, 2003. |
| Bookmark as: | http://hdl.handle.net/10022/AC:P:5490 |
| Full Text (ProQuest): | /ac/proxit.jsp?url=http://gateway.proquest.com/ope... |
| Abstract: | A method is described for reversing the usual regioselectivity in the hydroformylation of allylic alcohols. Using the hydroxyl group as a handle, a phosphole tether is attached which directs the hydroformylation to give greater than 20:1 selectivity for the branched aldehyde. In the case of alpha-substituted alcohols, the hydroformylation proceeds in up to 96:4 selectivity favoring the anti diastereomer. In the case of methallyl alcohol, an unprecedented reversal of regioselectivity is achieved, with the quaternary aldehyde favored over the less branched product in a 12:1 ratio. Additionally, a series of 1,2-aminoalcohol-derived phosphine-sulfonamide ligands are shown to be useful in Cu-catalyzed conjugate addition of dialkylzinc reagents to enones. These ligands are conveniently synthesized and provide optimum selectivity at room temperature, affording greater than 96% enantiomeric excesses for a range of cyclic ketones, as well as the highest enantioselectivities yet observed in the production of isopropyl-substituted ketones. Modification of these ligands has led to new "tripodal" N-P-N compounds which show promise in conjugate addition with acyclic enones. Efforts towards adaptation of this methodology to employ Grignard reagents are also described. |
| Collection(s): | Doctoral Dissertations |
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