- Metal-Free Br?nsted Acid-Catalyzed Rearrangement of δ-Hydroxyalkynones to 2,3-Dihydro-4 H-pyran-4-ones: Total Synthesis of Obolactone and a Catechol Pyran Isolated from Plectranthus sylvestris
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A metal-free, Br?nsted acid, pTsOH-catalyzed intramolecular rearrangement of δ-hydroxyalkynones to substituted 2,3-dihydro-4H-pyran-4-ones was developed. The rearrangement occurs with high regioselectivity under mild and open-air conditions. The scope of work was illustrated by synthesizing an array of aliphatic and aromatic substituted 2,3-dihydro-4H-pyran-4-ones in up to 96% yield, 100% atom economy, and complete regioselectivity. Some of the dihydropyranones are utilized for vinylic halogenations and to complete the total synthesis of bioactive natural products, obolactone and a catechol pyran isolated from Plectranthus sylvestris (Labiatae).
- Gholap, Sachin P.,Jangid, Dashrath,Fernandes, Rodney A.
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- Cationic gold(I)-catalyzed intramolecular cyclization of γ-hydroxyalkynones into 3(2H)-furanones
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"Chemical Equation Presented" The combination of (p-CF 3C6H4)3PAuCl and AgOTf generates a powerful catalyst for the intramolecular cyclizations of readily available y-hydroxyalkynones un-der mild conditions. The
- Egi, Masahiro,Azechi, Kenji,Saneto, Moriaki,Shimizu, Kaori,Akai, Shuji
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supporting information; experimental part
p. 2123 - 2126
(2010/06/12)
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