- Functionalization of (2S)-Isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4- ones by a Suzuki-Miyaura Cross-Coupling Reaction Using Aryltrifluoroborate Salts: Convenient Enantioselective Preparation of α-Substituted β-Amino Acids
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A simple protocol for the Pd(OAc)2-catalyzed cross-coupling reaction of 1-benzoyl-(2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-ones with potassium aryltrifluoroborates was developed. The reaction is performed at 110°C with a ligand-free catalyst. In all cases, complete conversion of the 1-benzoyl-(2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-onesand aryltrifluoroborates into the C-C coupling products was observed within 30-360 min. It is noteworthy that a largevariety of groups present in the potassium aryltrifluoroborates (-CF3, -OMe, -SEt, -CN, -CHO, -Cl, -Cbz, -NCbz,-OH, -CO2H) could be tolerated. Hydrogenation of the endocyclic double bonds in the Suzuki-Miyaura products followed by acid hydrolysis afforded highly enantioenrichedα-aryl-substituted β-amino acids. We present a general approach for the synthesis of (2S)-isopropyl-5-aryl-2,3- dihydro-4(H)-pyrimidin-4-ones by Suzuki-Miyaura reaction of aryltrifluoroborate salts with(2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-ones in the presence of a palladium catalyst and a base. The arylated compounds were transformed into enantioenriched α-aryl-substituted β-amino acids. Copyright
- Stefani, Helio A.,Amaral, Monica F. Z. J.,Reyes-Rangel, Gloria,Vargas-Caporali, Jorge,Juaristi, Eusebio
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experimental part
p. 6393 - 6403
(2011/02/21)
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- Highly efficient palladium-catalyzed Suzuki-Miyaura reactions of potassium aryltrifluoroborates with 5-iodo-1,3-dioxin-4-ones in water: an approach to α-aryl-β-ketoesters
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The high efficient palladium-catalyzed Suzuki-Miyaura reactions of potassium aryltrifluoroborates 3 with 5-iodo-1,3-dioxin-4-ones 2a-b in water as only solvent in the presence of n-Bu4NOH as base is reported. The respective 5-aryl-1,3-dioxin-4-ones 4a-n were obtained in good to excellent yields. The catalyst system provides high efficiency at low load using electronically diverse coupling partners. The obtained 2,2,6-trimethyl-5-aryl-1,3-dioxin-4-ones were transformed into corresponding α-aryl-β-ketoesters 6 by reaction with an alcohol in the absence of solvent.
- Vieira, Adriano S.,Cunha, Rodrigo L.O.R.,Klitzke, Clécio F.,Zukerman-Schpector, Julio,Stefani, Hélio A.
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body text
p. 773 - 779
(2010/09/09)
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