Chalcone glucose

Chiral monoaza-crown ethers containing glucose units have been applied as phase-transfer catalysts in the Michael addition of 2-nitropropane to a chalcone to give the corresponding adduct in up to 90% ee. (Eq. 4.138).202... 

Figure 5.4. Abbreviated scheme for biosynthesis of major flavonoid subclasses, showing the primary enzymes and substrates leading to different subclasses. Bold-faced, uppercase abbreviations refer to enzyme names, whereas substrate names are presented in lowercase letters. PAL, phenylalanine ammonia lyase C4H, cinnamate 4-hydroxylase 4CL, 4-coumarate CoA ligase CHS, chalcone synthase CHI, chalcone isomerase CHR, chalcone reductase IPS, isoflavone synthase F3H, flavonone 3-hydroxylase F3 H, flavonoid 3 -hydroxylase F3 5 H, flavonoid 3 5 -hydroxylase FNSI/II, flavone synthase DFR, dihydroflavonol 4-reductase FLS, flavonol synthase ANS, anthocyanidin synthase LAR, leucoanthocyanidin reductase ANR, anthocyanidin reductase UFGT, UDP-glucose flavonoid 3-O-glucosyltransferase. R3 = H or OH. R5 = H or OH. Glc = glucose. Please refer to text for more information.

Lewinsohn E, Britsch L, Mazur Y, Gressel J (1989) Flavanone glycoside biosynthesis in Citrus chalcone synthase, UDP-glucose flavanone-7-0-glucosy-transferase and -rhamnosyltransferase activities in cell-free extracts. Plant Physiol 91 1321-1328... 

Several other high inductions have been reported by using crown ethers as catalysts (Scheme 10.8). The Toke group has used a chiral crown 11 (Chart 10.2), which incorporates a glucose unit, for the addition of 2-nitropropane to a chalcone (Scheme 10.8) [38], Several other effective chiral crowns (12-17, Chart 10.2 and Scheme 10.8) are noted [24e,39-42,48b]. An interesting study of the Michael addition under both solvent-free (0% ee) and liquid-liquid conditions (up to 70% ee) was reported by Diez-Barra and co-workers, who also addressed the question of free -OH quats (28, 58% ee) verses O-benzyl quats (30, 46% ee) [43]. 

In the addition of 2-nitropropane to chalcone Toke et al. achieved 90% ee by using the D-glucose-derived chiral crown ether 38 as phase-transfer catalyst (Scheme 4.12) [19]. The related crown ether 39, with a pendant phosphonate group, afforded the chalcone adduct with 83% ee, albeit with only 39% chemical yield (Scheme 4.12) [20]. N-Alkylated or N-arylated derivatives of the crown ether 38 afforded lower ee (max. 60%) in the addition of 2-nitropropane to chalcone [21],... 

Fig. 1. Simplified diagram of the phenylpropanoid and flavonoid biosynthetic pathways. Enzymes that catalyze the reactions are placed on the left-hand side, and transcription factors on the right-hand side of the arrows. Both transcription factors for which their control over the enzymatic steps has been genetically proven, as well as transcription factors that have been shown to interact with promoters of the structural genes, are shown. PAL Phenylalanine ammonia lyase C4H cinnamate 4-hydroxylase 4CL 4-coumaroyl-coenzyme A ligase CHS chalcone synthase CHI chalcone-flavanone isomerase F3H flavanone 3(3-hydroxylase DFR dihydroflavonol 4-reductase AS anthocyanin synthase UFGT UDP glucose-flavonol glucosyl transferase RT anthocyanin rhamnosyl transferase...

Chiral monoaza-15-crown-5 derived from D-glucose 92 was shown to be another good catalyst in the asymmetric epoxidation of chalcones with tert-butylhydroper-oxide as the oxidant, with the highest enantioselectivity (94% ee) being reported by Bako (entry 4, Table 11.8) [71]. The tetracyclic C2-symmetric guanidiurn salt 93, which was prepared from (SJ-malic acid by Murphy, also showed excellent enantioselection in the asymmetric epoxidation of chalcone (entry 5) [72]. 

Carbohydrate-derived azacrown ethers have been intensely studied as phase-transfer catalysts for the conjugate addition of 2-nitropropane to chalcones [172]. Various structural modifications have been introduced both in the azacrown core and in the carbohydrate (o-glucose, o-mannitol, and o-mannose) unit in order to obtain good enantioselectivities, the best results been obtained with o-glucose and D-mannose derivatives 113-117 (Scheme 2.60). 

Chalcones (l,3-diaryl-2-propen-l-ones) are flavonoids lacking a heterocyclic C ring. Also this category of flavonoids displays a broad spectrum of bio activities such as anticancer, antifungal, antibacterial, antiviral, and anti-inflammatory properties (Calliste et al. 2001). Dihydrochalcones, which do not have a P double bond, comprise phloretin [P- (4-hydroxyphenyl) -1 -(2,4,6-trihydroxypropiophenone) and its glucoside, phlo-ridzin (phloretin 2- P-D-glucose). Comparison with structurally related compounds revealed that the antioxidant pharmacophore of phloretin is 2,6-dihydroxyacetophenone (Rezk et al. 2002). The po-... 

Chiral Catalysts Containing Group 10 Metals (Ni, Pd, and Pt). The catalyst formed in situ from Ni(acac)2 and bomane aminoalcohols (DAB or DAIB) catalyze the enantioselective addition of diethylzinc to chalcones (254) (Fig. 21). Nickel(II)-chiral Schiff-base (the ligand derived from 1,2-diaminocyclohexane or 1,2-diaminopropane with pyrone derivative) complexes were efficient in epoxida-tion of nonfunctionalized olefins (255). Bis-ferrocenyl-triphosphane (PIGIPHOS) formed catalytically active complex with Ni(II) (256). Nickel-catalyzed asymmetric hydrocyanation of vinylarenes using glucose-derived phosphinite ligands was observed (257). 

Strawberry Strawberry/ antisense CaMV35S/OTS Chalcone synthase Chalcones Higher phenylpropanoids (100 versus 1 % control), cinnamoyl glucose caffeoyl glucose, feruloyl glucose, p-coumaryl alcohol and p-coumaryl-1-acetate [64]... 

Lakowicz quickly recognized the importance of stilbene boronic acid 6d and has since prepared several analogous ICT fluorophore systems, including oxazoline 8 [45], chalcones 9a,b [46] and boron-dipyrromethene (BODIPY) 10 [47]. The observed stability constants (Kapp) for 8 were 526 for D-fructose and 27 for D-glucose in 2 1 (v/v) water-medianol at pH 7.0 (phosphate buffer). J< pp for 9a,b were 400, 476 M" for D-fructose and 29, 33 M" for D-glucose in 2 1 (v/v) water-methanol at pH 6.5 (phosphate buffer). K pp for 10 were 1000 for D-fructose and 13.7 M" for D-glucose in water at pH 7.5 (phosphate buffer). 

Contains a complex mixture of red and yellow pigments including 20-30% safflower yellow (safflower yellow SY) which is composed of safflomin A (75%), SY-2 (15%), SY-3, and SY-4, all chalcones glycosides of chalcone (e.g., carthamin yellow) and qui-none (e.g., carthamone red), with the latter predominant in the commercial product also colorless flavonoids and flavonoid glycosides (carthamidin, isocarthamidin, neocarthamin) safflower polysaccharide (glucose, xylose. 

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