CHED 426 |
| β-Keto allyl esters were synthesized by the reaction of various alkenols with diketene using DMAP as a catalyst. The reactions led to yields that range from 79% to 91%. Creating a-substituted b-keto allyl esters by alkylation of the b-keto allyl esters with methyl iodide or benzyl bromide was also accomplished by using a base in THF. These reactions had obtained yields that range from 23% to 89%. The oxidative free-radical cyclization involves Mn(OAc)3/Cu(OAc)2. From this, four different b-keto allyl esters were shown to proceed via a 5-exo-trig-cyclization to afford the corresponding 5-membered lactones. Similar results were shown previously that involved substrates as β-diallyl esters and b-allyl keto esters. The products depend on the β-substituent of the β-keto allyl ester, the stereoselectivity of the intramolecular addition step, and the nature of the intermediate radical. Depending on the alpha substituent of the β-keto allyl esters, the products afforded 3,5 and 6,5 fused polycyclic carbocycles. |
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Undergraduate Research Poster Session: Organic Chemistry
11:00 AM-1:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Poster
Division of Chemical Education |