ORGN 822 |
| 5-Cyanouracil is an intermediate to 5-FU, which is a well-known antitumor agent. We developed a multi-component reaction to obtain 5-cyanouracils, but sometimes it generated a non-cyclized product, Z-1. Adding NEt3 to the reaction system could help the ring closure of Z-1a~c. Kinetic studies indicated the ring-closure reactions of Z-1a~c are general-base catalysis. The PKIE of kH/kD = 1.40, the Brønsted b value of 0.174, and reduction of the NEt3-catalyzed ring-closure rates by bulky or electron-withdrawing N-substituents confirm that the mechanism for the general-base catalyzed ring-closure reactions of Z-1a~c involves the rate-determining simultaneous proton transfer and intramolecular nucleophilic addition, followed by elimination of ethoxide.
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Total Synthesis, Materials, Molecular Recognition, Process R&D, and Physical Organic Chemistry
8:00 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster
Sci-Mix
Division of Organic Chemistry |
