- Highly enantioselective and efficient synthesis of flavanones including pinostrobin through the rhodium-catalyzed asymmetric 1,4-addition
-
An efficient synthesis of bioactive chiral flavanones (1) was achieved through the αh-catalyzed asymmetric 1,4-addition of arylboronic acid to chromone. The reaction in toluene proceeded smoothly at room temperature in the presence of 0.5% Rh catalyst with electron-poor chiral diphosphine MeO-F 12-BIPHEP. In this reaction, the 1,2-addition to (S)-1 frequently occurred to yield (2S,4α)-2,4-diaryl-4-chromanol as a byproduct, which could be reduced by changing the reaction solvent to CH2C 12 to deactivate the Rh catalyst (3% required).
- Korenaga, Toshinobu,Hayashi, Keigo,Akaki, Yusuke,Maenishi, Ryota,Sakai, Takashi
-
p. 2022 - 2025
(2011/06/28)
-
- Inter- and intramolecular Mitsunobu reaction based approaches to 2-substituted chromans and chroman-4-ones
-
Two approaches to optically active 2-substituted chromans and chroman-4-ones are described. The first utilized an intermolecular Mitsunobu reaction of a homochiral halopropanol and 2-bromophenol followed by cyclization to the 2-substituted chroman. In addition, a double lithiation procedure was developed to introduce additional functionality to the chroman. The second approach utilized an intramolecular Mitsunobu cyclization to give the 2-substituted chroman-4-one nucleus. The methodologies were applied to the syntheses of several biologically active natural and synthetic products.
- Hodgetts, Kevin J.
-
p. 6860 - 6870
(2007/10/03)
-
- Approaches to 2-substituted chroman-4-ones: Synthesis of (-)-pinostrobin
-
Two approaches to optically active 2-substituted chroman-4-ones are described. The first utilized the oxidation of a preformed chroman ring and the second an intramolecular Mitsunobu cyclization. The methodology was applied to the synthesis of the biologically active natural product (-)-pinostrobin (18).
- Hodgetts, Kevin J.
-
p. 3763 - 3766
(2007/10/03)
-
- FLAVONOID 5-GLUCOSIDES FROM PRUNUS CERASUS BARK AND THEIR CHARACTERISTIC WEAK GLYCOSIDIC BONDING
-
Pinostrobin 5-glucoside, a novel flavanone glycoside, was isolated from the bark of Prunus cerasus.As it was not found in P. avium, the substance is useful to distinguish these two species.Apigenin 5-glucoside, genkwanin 5-glucoside and neosakuranin were also isolated from the bark of P. cerasus.They occur in both species as minor components.These 5-glucosides together with genistein 5-glucoside, prunetin 5-glucoside, sakuranin, tectochrysin 5-glucoside and luteolin 5-glucoside were hydrolysed in malic acid.The isoflavone and flavone 5-glucosides were shown to be hydrolysed more rapidly than the flavanone 5-glucosides, whereas no hydrolysis was observed with the corresponding 7-glucosides under the same conditions.The chalcone 2'-glucoside neosakuranin was transformed at first to the corresponding flavanone 5-glucoside, which was hydrolysed thereafter. Key Word Index - Prunus cerasus; Prunus avium; Rosaceae; bark; pinostrobin 5-glucoside; flavonoid 5-glucosides; hydrolysis.
- Geibel, Martin,Feucht, Walter
-
p. 1519 - 1521
(2007/10/02)
-
