1029-94-3Relevant academic research and scientific papers
Photoinduced Aerobic Iodoarene-Catalyzed Spirocyclization of N-Oxy-amides to N-Fused Spirolactams**
Cariou, Kevin,Habert, Lo?c
, p. 171 - 175 (2021)
Iodoarene catalysis is a powerful methodology that usually requires an excess of oxidant, or of redox mediator if the terminal oxidant is dioxygen, to generate the key hypervalent iodine intermediate to proceed efficiently. We report that, using the spiro-cyclization of amides as a benchmark reaction, aerobic iodoarene catalysis can be enabled by relying on a pyrylium photocatalyst under blue light irradiation. This unprecedented dual organocatalytic system allows the use of low catalytic loading of both catalysts under very mild operating conditions.
Direct synthesis of γ-pyrones by electrophilic condensation of β-ketoesters
Rodrigues, Catarina A. B.,Misale, Antonio,Schiel, Florian,Maulide, Nuno
, p. 680 - 683 (2017)
Triflic anhydride is a versatile electrophile that is able to activate poor nucleophiles. Herein, we show that readily available β-keto esters are activated by Tf2O furnishing γ-pyrones. Mechanistic studies suggest that this transformation proceeds via a double triflation, formation of an oxocarbenium intermediate and dealkylation promoted by a crucial nitrile additive.
Regiodivergent Hydration-Cyclization of Diynones under Gold Catalysis
Mu?oz, Miguel A.,Sanz, Roberto,Solas, Marta,Suárez-Pantiga, Samuel
supporting information, p. 7681 - 7687 (2020/10/12)
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.
Synthetic studies on a series of functionalized pyrylium salts, 4-chloro- and 4-bromophosphinines
Nagahora, Noriyoshi,Tokumaru, Hiroshi,Ikaga, Shinpei,Hanada, Takuya,Shioji, Kosei,Okuma, Kentaro
, p. 1880 - 1887 (2018/03/07)
A series of new pyrylium salts that bear sulfonate and phosphonate groups were obtained from the reactions between 2,6-diphenyl-4H-pyran-4-one, sulfonic anhydride, and chlorophosphates, and analyzed spectroscopically. Furthermore, treatment of 2,6-diphenyl-4H-pyran-4-one with phosphoryl chloride or bromide afforded the corresponding 4-chloro- and 4-bromopyrylium tetrafluoroborates in good yield. Subsequently, the synthesis of the corresponding 4-chloro- and 4-bromophosphinines was accomplished by treating the respective chloro- and bromopyrylium tetrafluoroborates with tris(trimethylsilyl)phosphine.
Synthesis of γ-pyrones via decarboxylative condensation of β-ketoacids
Merad, Jérémy,Maier, Thomas,Rodrigues, Catarina A. B.,Maulide, Nuno
, p. 57 - 62 (2017/01/17)
Abstract: This manuscript describes the convergent synthesis of aryl- and alkyl-disubstituted γ-pyrones from β-ketoacids. The reaction proceeds in the presence of trifluoromethanesulfonic anhydride via an unprecedented decarboxylative auto-condensation of the starting material. Herein, the scope and limitations of this transformation are reported. Graphical abstract: [Figure not available: see fulltext.]
Redesign of a Pyrylium Photoredox Catalyst and Its Application to the Generation of Carbonyl Ylides
Alfonzo, Edwin,Alfonso, Felix Steven,Beeler, Aaron B.
, p. 2989 - 2992 (2017/06/07)
We report the exploration into photoredox generation of carbonyl ylides from benzylic epoxides using newly designed 4-mesityl-2,6-diphenylpyrylium tetrafluoroborate (MDPT) and 4-mesityl-2,6-di-p-tolylpyrylium tetrafluoroborate (MD(p-tolyl)PT) catalysts. These catalysts are excited at visible wavelengths, are highly robust, and exhibit some of the highest oxidation potentials reported. Their utility was demonstrated in the mild and efficient generation of carbonyl ylides from benzylic epoxides that otherwise could not be carried out by current common photoredox catalysts.
Asymmetric transfer hydrogenation of functionalized acetylenic ketones
Fang, Zhijia,Wills, Martin
, p. 8594 - 8605 (2013/09/24)
A systematic study of the asymmetric transfer hydrogenations of functionalized acetylenic ketones and diketones has been completed, together with a total synthesis of (S,S)-(-)-yashabushidiol B. In several cases, excellent enantioselectivities and yields
Bronsted acid catalyzed and NIS-promoted cyclization of diynones: Selective synthesis of 4-pyrone, 4-pyridone, and 3-pyrrolone derivatives
Qiu, Yi-Feng,Yang, Fang,Qiu, Zi-Hang,Zhong, Mei-Jin,Wang, Li-Jing,Ye, Yu-Ying,Song, Bo,Liang, Yong-Min
, p. 12018 - 12028 (2014/01/06)
Bronsted acid catalyzed tandem cyclization was found to be highly effective for the preparation of a series of polysubstituted 4-pyrones from diynones (yield up to 99%). 4-Pyridone and 3-pyrrolone derivatives were also selectively synthesized by employing NIS and/or Bronsted acid. NIS as an electrophilic reagent could promote these reactions efficiently and rapidly under very mild reaction conditions.
New strong base synthesis of symmetrical 1,5-diaryl-1,3,5-pentanetriones from acetone and benzoate esters
Knight, John D.,Metz, Clyde R.,Beam, Charles F.,Pennington, William T.,VanDerveer, Donald G.
, p. 2465 - 2482 (2008/09/21)
Lithium hexamethyldisilazide (LiHMDS) was used to condense substituted benzoate esters with acetone to afford symmetrical 1,5-diaryl-1,3,5- pentanetriones that were isolated, characterized (including a representative X-ray crystallographic analysis), and
Synthesis and acid- or base-catalyzed cyclization of various 4-pentyne-1,3-dione derivatives
Kuroda, Hirofumi,Izawa, Hironori
, p. 780 - 782 (2007/10/03)
4-Pentyne-1,3-dione derivatives having various substituents were conveniently synthesized from ynals and silyl enol ethers in two steps. The cyclization behaviors of the obtained 4-pentyne-1,3-diones were studied. γ-Pyrones and 3(2H)-furanones were obtain
