Expedient Approach to 6‐Bromo‐2‐isopropylidenecoumaranone,a Potential Intermediate for the Synthesis of TMC‐120B,Pseudodeflectusin, and Their Congeners |
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Authors: | Jorgelina L Pergomet Teodoro S Kaufman Andrea B J Bracca |
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Institution: | 1. Institute of Chemistry of Rosario (IQUIR, CONICET‐UNR) and School of Biochemical and Pharmaceutical Sciences, National University of Rosario, Rosario, Argentina;2. +54‐341‐4370477, ext. 103 |
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Abstract: | A straightforward approach toward 6‐bromo‐2‐isopropylidenecoumaranone, a potential intermediate toward alkaloid TMC 120‐B, pseudodeflectusin, and other natural products, was reported. The synthetic sequence involved the reaction of 3‐bromosalicylaldehyde with chloroacetone and cyclization of the resulting ether to a 2‐acetylcoumaranol intermediate. This was followed by sequential methyl Grignard addition and Jones’ oxidation to the corresponding coumaranone, which was dehydrated to the final product with the methanesulfonyl chloride/pyridine reagent. The protection of the coumaranol as the corresponding THP‐ether resulted in improved product yields. |
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Keywords: | 6‐Bromo‐2‐isopropylidenecoumaranone TMC‐120B Pseudodeflectusin Natural product synthesis Proline‐mediated cyclization |
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