- Regiodivergent Hydration-Cyclization of Diynones under Gold Catalysis
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Skipped diynones, efficiently prepared from biomass-derived ethyl lactate, undergo a tandem hydration-oxacyclization reaction under gold(I) catalysis. Reaction conditions have been developed for a switchable process that allows selective access to 4-pyrones or 3(2H)-furanones from the same starting diynones. Further application of this methodology in the total synthesis of polyporapyranone B was demonstrated.
- Mu?oz, Miguel A.,Sanz, Roberto,Solas, Marta,Suárez-Pantiga, Samuel
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p. 7681 - 7687
(2020/10/12)
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- Atom-economic synthesis of 4-pyrones from diynones and water
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Transition-metal-free synthesis of 4-pyrones via TfOH-promoted nucleophilic addition/cyclization of diynones and water has been developed. This transformation is simple, atom economical and environmentally benign, providing rapid and efficient access to s
- Xu, Yan-Li,Teng, Qing-Hu,Tong, Wei,Wang, Heng-Shan,Pan, Ying-Ming,Ma, Xian-Li
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- Synthesis of pyran-4-ones from isoxazoles
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A synthesis of mono-, di- and tri-substituted pyran-4-ones from isoxazoles is reported. The isoxazoles can be synthesized from readily available starting materials and undergo a reductive cleavage reaction with Mo(CO)6 to generate enamino keton
- Li, Chun-Sing,Lacasse, Edith
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p. 3565 - 3568
(2007/10/03)
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- Synthesis and reactions of reduced flavones
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The cycloadditions of a series of 4H-pyran-4-ones 3c-e with electron-rich dienes 11a,b to give reduced flavones 12 is described. The subsequent reactions of these reduced flavones with HCl, trifluoroacetic anhydride, ethyl anthranilate 19a and anthranilon
- Groundwater, Paul W.,Hibbs, David E.,Hursthouse, Michael B.,Nyerges, Miklos
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p. 163 - 169
(2007/10/03)
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- Thermal addition reaction of aroylketene with ethyl vinyl ether: Aromatic substituent effect on aroylketene reactivity
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A series of aroylketenes (2) generated by thermolysis of 5-aryl-2,3-dihydrofuran-2,3-diones (1) reacted with ethyl vinyl ether under a thermal condition to give 2,3-dihydro-4H-pyran-4-ones (3) and/or 4H-pyran-4-ones (4). In this reaction the electron withdrawing substituent (NO2, Cl) introduced into the aryl part enhanced the ketene reactivity (2b-e), while the electron donating one (OMe) did not affect its reactivity (2f-g) in a significant extent. The heteroaroylketenes (2h) and (2i) showed a fairly good reactivity.
- Toda, Jun,Saitoh, Toshiaki,Oyama, Taichi,Horiguchi, Yoshie,Sano, Takehiro
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p. 2457 - 2464
(2007/10/03)
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- Synthetic Applications of N-N Linked Heterocycles. Part 12. The Preparation of 4-Alkylthio- and 4-Arylthio-pyridines by Regiospecific Attack of Thioalkoxide Ions on N-(4-Oxopyridin-1-yl)pyridinium Salts
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Thiolate ions add regiospecifically to N-(4-oxopyridin-1-yl)pyridinium salts (2)-(7) to give in good to excellent yields only the 1,4-dihydropyridine adducts (8)-(13), regardless of whether or not the pyridone moiety carries substituents for sterically shielding the 2- and 6-positions of the pyridinium ring.The addition is believed to be thermodynamically controlled.Decomposition of the dihydro-adducts under free-radical conditions, or by pyrolysis, gives good yields of pyridin-4-yl thioethers (14) and (16) though the reaction failed with the 2-methyl adducts (9).An improved synthesis of 6-methyl-4-oxopyran-2-carboxylic acid is also described.
- Sammes, Michael P.,Leung, Christopher W. F.,Mak, Chi Keung,Katritzky, Alan R.
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p. 1585 - 1590
(2007/10/02)
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- A ONE-STEP SYHTHESIS OF γ-PYRONES
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The potassium enolate of 4-methoxy-3-buten-2-one reacts with acid chlorides anhydrides and acylimidazoles by C-acylation and in situ cyclization to afford 2-substituted γ-pyrones directly.
- Morgan, Ted A.,Ganem, Bruce
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p. 2773 - 2774
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF SUBSTITUTED γ-PYRONES
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An efficient and general synthetic method for various 2-mono- and 2,6-disubstituted γ-pyrones has been developed.This utilizes the C-acylation (70-85percent) of β-methoxy-α,β-enone lithium enolates 4 by acid chlorides 3 followed by the acid-catalyzed cycl
- Koreeda, Masato,Akagi, Hiroshi
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p. 1197 - 1200
(2007/10/02)
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