Biomimetic synthesis of natural silybin

Merlini, Lucio; Zanarotti, A.; Pelter, Andrew; Rochefort, Malcolm P.; Hänsel, Rudolf

doi:10.1039/c39790000695

Cited by 34 publications

(22 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The introduction of solvent effects in the calculation of the energy barriers is therefore necessary, although the method used is only qualitative. For the syn isomer, the smallest activation energy is found in the case of the attack on the less substituted carbon C 1 . Conversely, for the anti isomer, the smallest activation energy is obtained in the case of the attack on the more substituted carbon C 3 .…”

Section: Nucleophilic Attack On the η 3 -Allylpalladium Complexmentioning

confidence: 94%

Palladium‐Catalyzed Annulation of Aryl‐1,2‐diols and Propargylic Carbonates. Theoretical Study of the Observed Regioselectivities

et al. 2003

View full text Add to dashboard Cite

Methyl 1-methylprop-2-ynyl carbonate reacts with 3-and 4-substituted benzene-1,2-diols to give 2,3-dihydro-3-methyl-2-methylidene-1,4-benzodioxines, as a mixture of regioisomers in the case of methoxy-substituted diphenol, and a single regioisomer for the nitro-and the formyl-substituted diphenols. The oxyanion which attacks first corresponds to the less acidic hydroxy function, and the attack of the second oxyanion on the η 3 -allylpalladium intermediate is directed toward the more substituted carbon atom. In order to explain

show abstract

Section: Nucleophilic Attack On the η 3 -Allylpalladium Complexmentioning

confidence: 94%

Palladium‐Catalyzed Annulation of Aryl‐1,2‐diols and Propargylic Carbonates. Theoretical Study of the Observed Regioselectivities

et al. 2003

View full text Add to dashboard Cite

show abstract

“…To our best knowledge there is only one reference in the literature dealing with mass spectrometric fragmentation studies of chromenes, and this study used electron impact ionization (EI) mass spectrometry; the typical EI fragmentation of these compounds was found to be the loss of one of the substituents on C‐2, giving a stable benzopyrilium ion 5…”

Section: Methodsmentioning

confidence: 99%

Electrospray tandem mass spectrometry of 2H‐chromenes

Domingues

Oliveira

et al. 2004

Rapid Comm Mass Spectrometry

View full text Add to dashboard Cite

Several 2H-chromenes derived from carbazoles were analyzed by electrospray tandem mass spectrometry. The 2H-chromenes constitute an important class of compounds that exhibit photochromic activity. The fragmentation pathways of the protonated molecular species [M+H]+ were studied, and main fragmentation pathways of these compounds were identified. Fragmentation pathways of [M+D]+ ions were also studied in order to obtain information about the location of the ionizing proton or deuteron. It was found that the proton is not preferentially located on the nitrogen atom. The charge is preferentially located as a tertiary carbocation, resulting from the uptake of the proton (or deuteron) by the zwitterionic open structure of the chromenes. The major fragmentation occurred by cleavage of the gamma-bond relative to the carbocation center, leading to a fragment at m/z 191 (C5H11+ or C14H9N+), which are the most abundant fragment ions for almost all compounds. The presence of substituents in the chromene ring does not change this behavior. Other observed common fragmentation pathways included loss of CH3* (15 Da), loss of CO (28 Da), combined loss of CO and CH3 (43 Da), and loss of the phenyl ring via combined loss of C6H4 and CH3* (-91 Da) and combined loss of C6H6 and CO (-106 Da).

show abstract

“…Two years later, Merlini et al 17 reported an enzyme-free oxidative coupling of taxifolin and coniferyl alcohol using Ag 2 O to yield a mixture of silibinin and isosilibinin. Based on those results, multiple researchers have reported biomimetic syntheses of flavonolignans and related analogues, typically using a silver oxidant.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Study of the Biomimetic Synthesis of Flavonolignan Diastereoisomers in Milk Thistle

et al. 2013

View full text Add to dashboard Cite

The mechanism for the biomimetic synthesis of flavonolignan diastereoisomers in milk thistle is proposed to proceed by single-electron oxidation of coniferyl alcohol, subsequent reaction with one of the oxygen atoms of taxifolin's catechol moiety, and finally, further oxidation to form four of the major components of silymarin: silybin A, silybin B, isosilybin A, and isosilybin B. This mechanism is significantly different from a previously proposed process that involves the coupling of two independently formed radicals.

show abstract

Biomimetic synthesis of natural silybin

Cited by 34 publications

References 0 publications

Palladium‐Catalyzed Annulation of Aryl‐1,2‐diols and Propargylic Carbonates. Theoretical Study of the Observed Regioselectivities

Palladium‐Catalyzed Annulation of Aryl‐1,2‐diols and Propargylic Carbonates. Theoretical Study of the Observed Regioselectivities

Electrospray tandem mass spectrometry of 2H‐chromenes

Mechanistic Study of the Biomimetic Synthesis of Flavonolignan Diastereoisomers in Milk Thistle

Contact Info

Product

Resources

About