- Stereoselective total synthesis of (S)- and (R)-nuciferine using benzyne chemistry
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Total syntheses of (S)- and (R)-nuciferine were accomplished through approach involving diastereoselective reaction between a chiral dihydroisoquinoline enamide and 2-(trimethylsilyl)phenyl trifluoromethanesulfonate promoted by CsF, affording a separable mixture of diastereoisomers, which provided (S)- and (R)-nuciferine via simple and efficient transformations.
- Casagrande, Gleison A.,Deflon, Victor M.,Martins, Gabriel R.,Oliveira-Silva, Diogo,Perecim, Givago P.,Pinto, Leandro M. C.,Raminelli, Cristiano
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- Alkaloid constituents from flower buds and leaves of sacred lotus (Nelumbo nucifera, Nymphaeaceae) with melanogenesis inhibitory activity in B16 melanoma cells
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Methanolic extracts from the flower buds and leaves of sacred lotus (Nelumbo nucifera, Nymphaeaceae) were found to show inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extracts, a new alkaloid, N-methylasimilobine N-oxide, was isolated together with eleven benzylisoquinoline alkaloids. The absolute stereostructure of the new alkaloid was determined from chemical and physicochemical evidence. Among the constituents isolated, nuciferine, N-methylasimilobine, (-)-lirinidine, and 2-hydroxy-1-methoxy-6a,7-dehydroaporphine showed potent inhibition of melanogenesis. Comparison of the inhibitory activities of synthetic related alkaloids facilitated characterization of the structure-activity relationships of aporphine- and benzylisoquinoline-type alkaloids. In addition, 3-30 μM nuciferine and N-methylasimilobine inhibited the expression of tyrosinase mRNA, 3-30 μM N-methylasimilobine inhibited the expression of TRP-1 mRNA, and 10-30 μM nuciferine inhibited the expression of TRP-2 mRNA.
- Nakamura, Seikou,Nakashima, Souichi,Tanabe, Genzo,Oda, Yoshimi,Yokota, Nami,Fujimoto, Katsuyoshi,Matsumoto, Takahiro,Sakuma, Rika,Ohta, Tomoe,Ogawa, Keiko,Nishida, Shino,Miki, Hisako,Matsuda, Hisashi,Muraoka, Osamu,Yoshikawa, Masayuki
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p. 779 - 787
(2013/02/25)
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- Aporphine alkaloid synthesis and diversification via direct arylation
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Palladium-catalyzed direct arylation of aryl chlorides, bromides and iodides has been applied to the preparation of new aporphine analogues including C2-substituted aporphines by reaction with benzodioxole, pyridine N-oxide and pyrazine N-oxide. Successful application of direct arylation in these diversification reactions highlights its utility not only in convergent, but also in divergent synthesis. We also describe enantioselective syntheses of (R)-nornuciferine and (R)-nuciferine employing a catalytic asymmetric transfer hydrogenation in high yield and excellent enantiomeric excess. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Lafrance, Marc,Blaquiere, Nicole,Fagnou, Keith
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p. 811 - 825
(2008/02/12)
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