Pinacol Rearrangement of 3,4‐Dihydro‐3,4‐dihydroxyquinolin‐2(1H)‐ones: An Alternative Pathway to Viridicatin Alkaloids and Their Analogs |
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| Authors: | Ond?ej Rudolf Michal Rouchal Antonín Ly?ka Antonín Klásek |
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| Institution: | 1. Department of Chemistry, Faculty of Technology, Tomas Bata University, CZ‐762 72 Zlín;2. Research Institute for Organic Syntheses (VUOS), Rybitví 296, CZ‐533 54 Pardubice 20;3. University of Hradec Králové, Faculty of Science, CZ‐500 03 Hradec Králové 3 |
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| Abstract: | 3‐Alkyl/aryl‐3‐hydroxyquinoline‐2,4‐diones were reduced with NaBH4 to give cis‐3‐alkyl/aryl‐3,4‐dihydro‐3,4‐dihydroxyquinolin‐2(1H)‐ones. These compounds were subjected to pinacol rearrangement by treatment with concentrated H2SO4, resulting in 4‐alkyl/aryl‐3‐hydroxyquinolin‐2(1H)‐ones. When a benzyl (Bn) group was present in position 3 of the starting compound, its elimination occurred during the rearrangement, and the corresponding 3‐hydroxyquinolin‐2(1H)‐one was formed. The reaction mechanisms are discussed for all transformations. All compounds were characterized by IR, 1H‐ and 13C‐NMR spectroscopy, as well as mass spectrometry. |
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| Keywords: | Alkaloids β ‐Dicarbonyl compounds Debenzylation Pinacol rearrangement |
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