ORGN 375 |
| Computed enthalpies of formation for various Lewis acids and representative unsaturated compounds (aldehydes, imines, alkynes, and alkenes) provide a means to evaluate the applicability of a particular catalyst in a catalytic reaction. As expected, main group Lewis acids such as BX3 show much stronger complexes with the heteroatoms than with c-c multiple bonds σ-electrophilic LA). Gold and copper salts with non-nucleophilic anions increase the relative strength of coordination to the c-c multiple bonds (π-electrophilic LA). As representative examples for the use of σ-electrophilic LA, the allylation reactions of aldehydes with allylic organometallics were applied for the synthess of polycyclic ether marine natural products, such as Hemibrevetoxin B, Gambierol, and Brevetoxin B. As representative examples for the use of π-electrophilic LA, gold catalyzed benzannulation of orth-alkynylaldehydes with alkynes was applied for the short synthesis of (+)-ochromycinone.
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Arthur C. Cope and Arthur C. Cope Scholars Awards
8:00 AM-12:05 PM, Tuesday, August 21, 2007 BCEC -- Ballroom, Oral
Division of Organic Chemistry |
