17060-20-7Relevant articles and documents
ELECTROCHEMICAL TRANSFORMATIONS OF 2'-HYDROXYCHALCONES INTO FLAVANOIDS
Sanicanin, Zivko,Tabakovic, Ibro
, p. 407 - 408 (1986)
2'-Hydroxychalcones are cyclized to flavanones, and flavone, or flavonol, by electrochemically generated tris-(4-bromophenyl)amine cation radical as homogeneous electron-transfer agent.
Attrition-enhanced deracemization and absolute asymmetric synthesis of flavanones from prochiral precursors
Kasashima, Yoshio,Mino, Takashi,Sakamoto, Masami,Shimizu, Waku,Uemura, Naohiro,Yoshida, Yasushi
, p. 5676 - 5681 (2020/10/13)
Seven racemic 5,7-dimethoxyflavanones afforded conglomerate crystals upon recrystallization from a solvent. Three methodologies were investigated to achieve asymmetric transformation based on dynamic crystallization of the chiral conglomerate system. The first was chiral symmetry breaking of racemic flavanones by attrition-enhanced deracemization. Continuous suspension of racemic flavanones in a small amount of propanol in the presence of a base (1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)) and glass beads promoted chiral symmetry breaking and converted the flavanones to crystals of (+)- or (-)-enantiomers with 78 to 99% ee. The second method involved cyclization of the intermediate aldol product to give optically active flavanone with 90% ee involving a reversible oxa-Michael addition reaction with attrition-enhanced deracemization. The third was a reaction starting from prochiral 2-hydroxy-4,6-dimethoxyacetophenone and 2-naphthaldehyde under basic conditions, which gave the corresponding flavanone in 89% ee.
Synthesis of isoflavones containing naturally occurring substitution pattern by oxidative rearrangement of respective flavanones using thallium(III) p-tosylate
Singh, Om V.,Muthukrishnan,Sunderavadivelu
, p. 2575 - 2581 (2007/10/03)
Claisen condensation of substituted 2′-hydroxyacetophenones 1a-c with aromatic aldehydes affords respective substituted 2′-hydroxychalcones 2a-n which on base catalyzed cyclization in pyridine:methanol:water (1:1:1) give respective flavanones 3a-n. The oxidative rearrangement of flavanones with thallium(III) p-tosylate furnishes respective isoflavones 4a-n in overall 62-72% yields starting from 1. The present methodology has been successfully applied for the synthesis of naturally occurring isoflavones such as di-O-methyldaidzein 4a, cabruvin 4b, pseudobabtigenin methylether 4d, 5,7-dimethoxyisoflavone 4f, 5,7,4′-trimethoxyisoflavone 4g, derrustone 4i, 7,8,3′,4′- tetramethoxyisoflavone 41, purpuranin-A 4m and 7,8,3′,4′,5′- pentamethoxyisoflavone 4n and thus the first synthesis of 4n is reported.
Synthesis of a Typical Chalkone and a Flavanone of Wyethia glabra
Babber, Sunanda,Chandra, S.,Aggarwal, Anil K.
, p. 797 - 798 (2007/10/02)
The constitution of a new chalkone as 2',4',6'-trihydroxy-4-methoxychalkone (1), isolated from Wyethia glabra has now been confirmed by its synthesis using 2'-hydroxy-4',6'-dibenzoyloxy-4-methoxychalkone (1a) as an essential intermediate.The structure of another compound as 5,3',4'-trihydroxy-7-methoxyflavanone (2) (eriodictyol-7-methyl ether) isolated from the same source, has also been confirmed by its synthesis using vanillin as the starting material.
