Synthesis, Spectroscopic, and in Vitro Photosensitizing Efficacy of Ketobacteriochlorins Derived from Ring-B and Ring-D Reduced Chlorins via Pinacol鈥揚inacolone Rearrangement

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• 作者：Penny Joshi ; Manivannan Ethirajan ; Lalit N. Goswami ; Avinash Srivatsan ; Joseph R. Missert ; Ravindra K. Pandey
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：November 4, 2011
• 年：2011
• 卷：76
• 期：21
• 页码：8629-8640
• 全文大小：692K
• 年卷期：v.76,no.21(November 4, 2011)
• ISSN：1520-6904

文摘

In this report, we present a regioselective oxidation of a series bacteriochlorins, which on reacting with either ferric chloride (FeCl₃) or 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) yielded the corresponding ring-B or ring-D reduced chlorins. The effect of the number of electron-withdrawing groups present at the peripheral position, with or without a fused isocyclic ring (ring-E), did not make any significant difference in regioselective oxidation of the pyrrole rings. However, depending on the nature of substituents, the intermediate bis-dihydroxy bacteriochlorins on subjecting to pinacol鈥損inacolone reaction conditions gave various ketochlorins. The introduction of the keto-group at a particular position in the molecule possibly depends on the stability of the intermediate carbocation species. The newly synthesized bacteriochlorins show strong long-wavelength absorption and produced significant in vitro (Colon26 cells) photosensitizing ability. Among the compounds tested, the bacteriochlorins containing a keto-group at position 7 of ring-B with cleaved five-member isocyclic ring showed the best efficacy.