ORGN 549 |
| Achiral templates play a pivotal role in most of the enantioselective radical chemistry reported in the literature to date. These auxiliaries provide a second donor atom that is vital for Lewis acid chelation. The use of achiral templates, however, requires two separate synthetic steps for their introduction and removal. We have recently been interested in developing new enantioselective radical additions onto substrates that will not require an achiral template. Hydroxy-pyrones represent a class of readily available compounds that function as auxiliary-independent substrates. The presentation will address several key issues for Lewis acid-catalyzed conjugate radical additions to hydroxy-pyrones: (1) how reactive are they towards conjugate radical additions? (2) what is the C-2 vs. C-6 regioselectivity and will electronic or steric issues control the regiochemistry? (3) what will be the optimal chiral Lewis acid system for stereoselectivity?
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Asymmetric Reactions and Syntheses
1:00 PM-5:00 PM, Wednesday, 31 August 2005 Washington DC Convention Center -- 201, Oral
Division of Organic Chemistry |
