- Reversed-polarity synthesis of diaryl ketones through palladium-catalyzed direct arylation of 2-Aryl-1,3-dithianes
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An umpolung approach to the synthesis of diaryl ketones has been developed based on in situ generation of acyl anion equivalents and their catalytic arylation. This method entails the base-promoted, palladium-catalyzed direct C-H arylation of 2- aryl-1,3-dithianes with aryl bromides. Use of ( SiMe3)2 (M=Li, Na) base results in reversible deprotonation of the weakly acidic dithiane. In the presence of a Pd(NiXantphos)-based catalyst and aryl bromide, cross-coupling of the metallated 2-aryl- 1,3-dithiane takes place under mild conditions (2 h at rt) with yields as high as 96%. The resulting 2,2- diaryl-1,3-dithianes were converted into diaryl ketones by either molecular iodine, N-bromo succinimide (NBS) or Selectfluor in the presence of water. The dithiane arylation/hydrolysis can be performed in a one-pot procedure to yield a variety of diaryl ketones in good to excellent yields. This method is suitable for rapid and large-scale synthesis of diaryl ketones. A one-pot preparation of anti-cholesterol drug fenofibrate (TriCor) has been achieved on 10.0 mmol scale in 86% yield.
- Yucel, Baris,Walsh, Patrick J.
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p. 3659 - 3667
(2015/01/09)
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- Reversed-polarity synthesis of Diaryl Ketones through palladium-catalyzed direct Arylation of 2-Aryl-1,3-dithianes
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An umpolung approach to the synthesis of diaryl ketones has been developed based on in situ generation of acyl anion equivalents and their catalytic arylation. This method entails the base-promoted, palladium-catalyzed direct C-H arylation of 2- aryl-1,3-dithianes with aryl bromides. Use of MNACHTUNGTRENUNG( SiMe3)2 (M=Li, Na) base results in reversible deprotonation of the weakly acidic dithiane. In the presence of a Pd(NiXantphos)-based catalyst and aryl bromide, cross-coupling of the metallated 2-aryl- 1,3-dithiane takes place under mild conditions (2 h at rt) with yields as high as 96%. The resulting 2,2- diaryl-1,3-dithianes were converted into diaryl ketones by either molecular iodine, N-bromo succinimide (NBS) or Selectfluor in the presence of water. The dithiane arylation/hydrolysis can be performed in a one-pot procedure to yield a variety of diaryl ketones in good to excellent yields. This method is suitable for rapid and large-scale synthesis of diaryl ketones. A one-pot preparation of anti-cholesterol drug fenofibrate (TriCor) has been achieved on 10.0 mmol scale in 86% yield.
- Yucel, Baris,Walsh, Patrick J.
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supporting information
p. 3659 - 3667
(2015/01/09)
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- 1,3-Dithienium and 1,3-Dithiolenium Salts, VI. - N,N-Disubstituted 4-Aminobenzophenones from 1,3-Dithian- and 1,3-Dithiolan-2-ylium Tetrafluoroborates, respectively
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The 1,3-dithienium- and 1,3-dithiolenium tetrafluoroborates 3 (n =3, 2), respectively, react in good yields with the N,N-dialkylarylamines 4 to give the 2,2-disubstituted cyclic dithio acetals 5, which can be converted after dethioacetalization with HgCl2/HgO into the ketones 7.
- Stahl, Ingfried
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p. 135 - 140
(2007/10/02)
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