Lignans fromKrameria ixina

Achenbach, Hans; Utz, Wolfgang; Usubillaga, Alfredo; Rodriguez, Henry A.

doi:10.1016/0031-9422(91)80103-8

Cited by 37 publications

(27 citation statements)

References 16 publications

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“…For this reason, the present work assignment of NMR data on the basis of 1D and 2D experiments (Table 1S and 2S, Supporting Information) was completed. Cycloartane triterpenes have been isolated in K. parvifolia [5], K. grayi [4], and K. ixina [27]. On the other hand, E-3,5-dimethoxy-4-[6-(prop-1-enyl)benzofuran-2]-yl-phenol was isolated in this work and its spectroscopic data were compared with those reported in the literature.…”

Section: Resultsmentioning

confidence: 82%

Cycloartanes from Krameria pauciflora and Their In Vitro PLA2, COX-1, and COX-2 Enzyme Inhibitory Activities

et al. 2012

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Krameria pauciflora is a species belonging to the Krameriaceae family. It has been used to treat inflammatory disorders in folkloric Mexican medicine; however, chemistry and pharmacological studies have not been carried out on this species. In this work, from the dichloromethane root extract of K. pauciflora, five cycloartane-type triterpenoids were isolated: cyclomargenyl-3-O-β-caffeoyl ester (1), cyclomargenyl-3-O-β-feruloyl ester (2), cyclomargenyl-3-O-β-coumaroyl ester (3), cyclomargenol (4, polysthicol), and cyclomargenone (5). Additionally, the lignane 6'-methoxyrataniaphenol was isolated. To the best of our knowledge, compounds 1-3 are new natural products, whereas compounds 4 and 5 are isolated for the first time in the Krameria genus and the Krameriaceae family. The structures of all of these compounds were established by 1D and 2D NMR spectroscopy including ¹H, ¹³C, DEPT, COSY, HSQC, and HMBC experiments, as well as by EI mass spectrometry. There is an incomplete previous report about the spectroscopic data of compounds 4 and 5. However, in this work, a complete and unambiguous assignation has been realized. Due to the traditional use of this plant and other species from this genus, such as K. lappacea, cycloartanes isolated herein were evaluated by their inhibition of phospholipase A₂, cyclooxygenase-1, and cyclooxygenase-2 enzymes. Cyclomargenyl-3-O-β-caffeoyl ester (1) showed inhibition of phospholipase A₂, cyclooxygenase-1, and cyclooxygenase-2 target enzymes for nonsteroidal anti-inflammatory drugs. Both cyclooxygenases were inhibited by cyclomargenol (4); however, cyclomargenyl-3-O-β-feruloyl ester (2) showed inhibition only on cyclooxygenase-1.

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Section: Resultsmentioning

confidence: 82%

Cycloartanes from Krameria pauciflora and Their In Vitro PLA2, COX-1, and COX-2 Enzyme Inhibitory Activities

et al. 2012

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“…Chemie ing para or ortho alkoxy groups were the most reactive cycloaddition partners (19)(20)(21). However, styrenes lacking these activating groups still reacted smoothly (22-24).…”

Section: Methodsmentioning

confidence: 99%

“…Communications product in 81 % yield over these two steps. Similarly, the antiprotozoal neolignan 37, isolated from K. ixina, [20] is available in three steps from cycloadduct 7. Selective hydrogenolysis of the primary benzyl ether followed by treatment with triflic anhydride affords aryl triflate 36 in 93 % yield over two steps.…”

Section: Methodsmentioning

confidence: 99%

Photocatalytic Synthesis of Dihydrobenzofurans by Oxidative [3+2] Cycloaddition of Phenols

Blum¹,

Zhu²,

Nordeen³

et al. 2014

Angew Chem Int Ed

111

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“…Subsequent deprotection of the silyl group affords the natural product in 81 % yield over these two steps. Similarly, the antiprotozoal neolignan 37 , isolated from K. ixina ,20 is available in three steps from cycloadduct 7 . Selective hydrogenolysis of the primary benzyl ether followed by treatment with triflic anhydride affords aryl triflate 36 in 93 % yield over two steps.…”

Section: Optimization Of Conditions For Oxidative [3+2] Cycloadditionmentioning

confidence: 99%

Photocatalytic Synthesis of Dihydrobenzofurans by Oxidative [3+2] Cycloaddition of Phenols

2014

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We report a protocol for oxidative [3+2] cycloadditions of phenols and alkenes applicable to the modular synthesis of a large family of dihydrobenzofuran natural products. Visible light-activated transition metal photocatalysis enables the use of ammonium persulfate as an easily handled, benign terminal oxidant. The broad range of organic substrates that are readily oxidized by photoredox catalysis suggests that this strategy may be applicable to a variety of useful oxidative transformations. Keywords cycloaddition; heterocycles; phenols; photocatalysis; photooxidationThe choice of terminal oxidant is important in the design of oxidative reactions. 1 Many of the most commonly used oxidants produce stoichiometric byproducts that can be practically or environmentally problematic. Our laboratory has a long-standing interest in the propensity of photoexcited Ru*(bpy) 3 2+ to undergo redox reactions with a diverse range of quenchers, 2 a feature that has been increasingly exploited in the design of synthetic reactions. 3 We wondered if photoredox catalysis might offer a general strategy to employ benign, kinetically inert oxidants in oxidative transformations. Recent interest in photoredox catalysis has largely been focused on redox-neutral and net reductive reactions; the examples of net oxidative transformations published to date have generally utilized either stoichiometric halocarbon oxidants, 4 which are not ideal from an environmental standpoint, or molecular oxygen, 5 which is a triplet quencher of many photoexcited molecules 6 that can negatively impact the overall efficiency of photocatalytic reactions. Thus, there exists a need for a more practical, general approach to the design of oxidative photoredox reactions.We became interested in studying phenol oxidation as a starting point to explore this challenge. Phenols participate in a rich variety of oxidatively induced transformations, 7

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Lignans fromKrameria ixina

Cited by 37 publications

References 16 publications

Cycloartanes from Krameria pauciflora and Their In Vitro PLA2, COX-1, and COX-2 Enzyme Inhibitory Activities

Cycloartanes from Krameria pauciflora and Their In Vitro PLA2, COX-1, and COX-2 Enzyme Inhibitory Activities

Photocatalytic Synthesis of Dihydrobenzofurans by Oxidative [3+2] Cycloaddition of Phenols

Photocatalytic Synthesis of Dihydrobenzofurans by Oxidative [3+2] Cycloaddition of Phenols

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