CHED 494 |
| Photoactivated enediynes have been widely studied over the past ten years. Our group is interested in the syntheses of highly conjugated enediynes to pursue photocyclization with visible light. One approach to increase the wavelength of light absorbed by an arenediyne chromophore is to increase conjugation via benzannelation. Condensation of 9,10-phenanthrenequinone with 4,5-diethynyl-1,2-diamino benzene derivatives readily affords 6,7-diethynylquinoxalenediyne analogs containing a fused phenanthrene ring. Using this methodology we have prepared 6,7-bis(ethynyl), 6,7-bis(phenylethynyl), and 6-ethynyl-7-phenylethynyl derivatives of phenanthroquinoxalenediyne. While the terminal model absorbs visible light it does not undergo efficient photocyclization. In contrast, the bis(phenylethynyl) derivative undergoes an unusual C1-C5 photocyclization at 300 nm producing an indenyl product. Current investigations are being directed at the photoreactivity of the mono(phenylethynyl) derivative at 300 nm and photoreactivity of all derivatives with visible light. The photoreactivity of these models will provide insights into the effect of extended benzannelation and steric bulk on enediyne photoreactivity. |
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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 |