1621-61-0Relevant articles and documents
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Shamma,Stiver
, p. 3887,3893 (1969)
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Enantioselective Synthesis of Isoflavanones and Pterocarpans through a RuII-Catalyzed ATH-DKR of Isoflavones
Caleffi, Guilherme S.,Costa, Paulo R. R.,Costa-Júnior, Paulo C. T.,Gaspar, Francisco V.
, p. 5097 - 5108 (2021/10/20)
Noyori-Ikariya RuII complexes promoted the one-pot C=C/C=O bonds reduction of isoflavones using sodium formate as the hydrogen source through Asymmetric Transfer Hydrogenation-Dynamic Kinetic Resolution (ATH-DKR). Due to the neutral conditions employed, isoflavones with different substituents at the 2’-position of B-ring (H, OH, OMe and Br) were successfully reduced. Ten cis-3-phenylchroman-4-ols were selectively obtained (>20 : 1 dr) in good yields (up to 86 %) and excellent enantioselectivities (up to >99 : 1 er). The synthetic applications of these chiral compounds were also demonstrated. Enantioenriched isoflavanones were obtained under mild metal-free oxidation of the cis-3-phenylchroman-4-ols while pterocarpans were synthesized by two strategies: an acid-catalyzed cyclization and a novel approach based on a Pd-catalyzed C?O intramolecular cross-coupling reaction.
Stille coupling for the synthesis of isoflavones by a reusable palladium catalyst in water
Chang, Ya-Ting,Liu, Ling-Jun,Peng, Wen-Sheng,Lin, Lin-Ting,Chan, Yi-Tsu,Tsai, Fu-Yu
, p. 469 - 475 (2021/02/03)
Isoflavones were synthesized from the reaction of 3-bromochromone derivatives and aryltributylstannanes via Stille coupling catalyzed by a water-soluble and reusable PdCl2(NH3)2/2,2′-cationic bipyridyl system in aqueous solution. For prototype 3-bromochromone, the coupling reaction was performed at 80°C for 24 hr with 2.5 mol% catalyst in water in the presence of tetrabutylammonium fluoride. After the reaction, the aqueous solution could be reused for several runs, indicating that its activity was only slightly decreased. For substituted 3-bromochromones, the addition of NaHCO3 and a higher reaction temperature (120°C) were required to gain satisfactory outcomes. In addition, naturally occurring products, such as daidzein, could be obtained by this protocol via a one-pot reaction.
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.
