1202-10-4Relevant articles and documents
A versatile method for the synthesis of γ-pyrones
Beye, Garrison E.,Karagiannis, Athanasios,Kazemeini, Alieh,Ward, Dale E.
, p. 954 - 964 (2013/02/22)
A versatile three-step procedure to annulate a γ-pyrone onto a methylene ketone was developed involving (i) aldol reaction with a dithiolane-protected β-ketoaldehyde, (ii) oxidation of the aldol adduct to a β-diketone, and (iii) treatment of the resulting dithiolane-protected 1,3,5-trione with 2-iodoxybenzoic acid (IBX) and trifluoromethanesulfonic acid (triflic acid; TfOH) in acetonitrile at ambient temperature to give the corresponding γ-pyrone. Cyclization proceeded with IBX alone, but significantly improved yields were obtained with added acid, particularly triflic acid. A dithiolane was more effective than a dithiane or acyclic dithioacetal protecting group. The method was amenable to the preparation of a variety of substituted γ-pyrones simply by altering the initial aldol reactants. Overall yields of 50%-60% were obtained in six examples. The method was applied to prepare a key fragment for the total synthesis of baconipyrones A and C and siphonarin B.
Rate-accelerating effect by the neighboring-group participation of protecting groups in the dehydrative cyclization of 1,3,5-triketones
Sakakura, Akira,Watanabe, Hitoshi,Ishihara, Kazuaki
supporting information; experimental part, p. 2569 - 2572 (2009/05/27)
(Chemical Equation Presented) Neighboring-group participation of an acyl protecting group efficiently promotes the Bronsted acid-catalyzed dehydrative cyclization of 1,3,5-triketones to γ-pyrones, whereas a bulky silyloxy group in the β-position retards t
Mild conditions for cyclization of β-triketides to the corresponding γ-pyrones carrying adjacent chiral centers toward biomimetic synthesis of fully substituted γ-pyrone-containing natural products
Arimoto, Hirokazu,Nishiyama, Shigeru,Yamamuni, Shosuke
, p. 5619 - 5620 (2007/10/02)
Related to synthetic study on γ-pyrone-containing natural products, conversions of β-triketides having unstable substituents to the corresponding γ-pyrones have successfully been accomplished by the new methods under conditions using (CH3)2S+C1 or Ph3P+CX3 (or Ph3P+X, X =C1, Br) as the oxygen acceptors.