- Functional group manoeuvring for tuning stability and reactivity: Synthesis of cicerfuran, moracins (D, E, M) and chromene-fused benzofuran-based natural products
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The protecting group manoeuvring as a strategy was applied for tuning the stability and reactivity of 4-(2,2-dibromovinyl)benzene-1,3-diol (12a) and 6-(2,2-dibromovinyl)-2,2-dimethylchroman-7-ol (22) in the domino synthesis of benzofuran-based natural products (1-8). The functional group demands and their impact on the reactivity driven by electronic effects were successfully managed by varying the protecting groups with substituted gem-dibromovinylphenols in domino couplings and triarylbismuth reagents under palladium-catalyzed conditions. This approach paved the way for the synthesis of moracin M (1) and cicerfuran (2), and the first time synthesis of moracin D (3) and moracin E (4) along with chromene-fused benzofuran-based natural products (5-8) in overall good yields.
- Rao, Maddali L. N.,Murty, Venneti N.,Nand, Sachchida
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- Total synthesis of moracin C
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Moracin C has been synthesised by the most efficient route to date (10 steps and 12% overall yield). The relatively unexplored acid-induced, intramolecular migration of an acyl group from an ortho phenolic hydroxy to a benzylic hydroxy is used to synthesise o-hydroxybenzylphosphonium salts containing ester groups. The phosphonium salts are coupled with 3,5-dimethoxybenzoic acid. Intramolecular Wittig reaction then gives 2-arylbenzo[b]furans, bearing the key 1′,3′,5′ substitution pattern on the aryl ring. This discovery provides a concise route to polyphenolic benzo[b]furans that we expect to be of general utility.
- McAllister, Graeme D.,Hartley, Richard C.,Dawson, Michael J.,Knaggs, Andrew R.
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p. 3453 - 3457
(2007/10/03)
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