Synthesis of dihydrodehydrodiconiferyl alcohol: the revised structure of lawsonicin

The structure of a nickel complex of imidazoline–aminophenol (IAP) prepared from IAP with Ni(OAc)2 was elucidated as cis‐bis(imidazolineaminophenoxide) [Ni(IAP)2]. The [Ni(IAP)2] complex smoothly promoted catalytic asymmetric 1,4‐addition of 3′‐indolyl‐3‐oxindole to nitroethylene to provide chiral mixed 3,3′‐bisindoles with high enantioselectivities. Mechanistic studies using ESI‐MS analyses suggest that one IAP ligand dissociated from [Ni(IAP)2] to generate the Ni–enolate of 3′‐indolyl‐3‐oxindole. From the optically active 3,3′‐mixed indole adduct, biologically important 3′‐indolyl‐3‐pyrrolidinoindoline was successfully synthesized in a three‐step reaction sequence.

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“…C66.65, H 6.71, O 26.63; found C 66.57, H 6.73, O 26.71. Physical and spectra data were found to be consistent with those reported 30c…”

Section: Methodssupporting

confidence: 87%

A Diastereoselective Route to trans‐2‐Aryl‐2,3‐dihydrobenzofurans through Sequential Cross‐Metathesis/Isomerization/Allylboration Reactions: Synthesis of Bioactive Neolignans

2015

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“…Model compounds β-O-4 GG, β-5, and β-β were synthesized according to the reported methods [23][24][25][26]. GVL (98%) was purchased from Macklin (Shanghai, China), sulfuric acid was obtained from Guangzhou Chemical Reagent (Guangzhou, China).…”

Section: Methodsmentioning

confidence: 99%

Revealing Structural Modifications of Lignin in Acidic γ-Valerolactone-H2O Pretreatment

Zhao

Yue

et al. 2020

Polymers

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γ-valerolactone (GVL)/H2O/acid solvent mixtures has been used in chemical pretreatment of lignocellulosic biomass, it was claimed that GVL lignins were structurally close to proto (native) lignins, or having low molecular weight with narrow polydispersity, however, the structural changes of GVL lignins have not been investigated. In this study, β-O-4 (β-aryl ether, GG), β-5 (phenylcoumaran), and β-β (resinol) lignin model compounds were treated by an acidic GVL-H2O solvent system, a promising pretreatment of lignocellulose for biomass utilization, to investigate the structural changes possibly related to the lignin involved. NMR characterization of the products isolated from the treated GG indicated that a phenyl dihydrobenzofuran, having typical C-H correlations at δC/δH 50.74/4.50 and 93.49/4.60 ppm in its HSQC spectrum, was produced from GG. In the pretreatment, the released formaldehyde from GG reacted fast with GG to form a novel 1,3-dioxane intermediate whose characteristic HSQC signals were: δC/δH 94.15–94.48/4.81–5.18 ppm and 80.82–83.34/4.50–4.94 ppm. The β-5 model, dihydrodehydrodiconiferyl alcohol, was converted into phenylcoumarone and stilbene having benzaldehyde that resulted from the allyl alcohol side chain. The β-β model, syringaresinol, was isomerized to form a mixture of syringaresinol, epi-, and dia-syringaresinol although being degraded slightly.

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“…6 Compounds incorporating this structural motif have been isolated from different species of higher plants for example, Asteraceae 5a,b. Toxol,5a a natural product of Encelia californica and lawsonicin,5d as well as other structurally related neolignans5e–h, 7b constitute representative examples of such naturally occurring 2,3‐dihydrobenzofurans (Scheme ). The biological activity of these systems is also well recognized 5a.…”

Section: Methodsmentioning

confidence: 99%

Taming the Friedel–Crafts Reaction: Organocatalytic Approach to Optically Active 2,3‐Dihydrobenzofurans

et al. 2011

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Synthesis of dihydrodehydrodiconiferyl alcohol: the revised structure of lawsonicin

Cited by 35 publications

References 42 publications

A Diastereoselective Route to trans‐2‐Aryl‐2,3‐dihydrobenzofurans through Sequential Cross‐Metathesis/Isomerization/Allylboration Reactions: Synthesis of Bioactive Neolignans

A Diastereoselective Route to trans‐2‐Aryl‐2,3‐dihydrobenzofurans through Sequential Cross‐Metathesis/Isomerization/Allylboration Reactions: Synthesis of Bioactive Neolignans

Revealing Structural Modifications of Lignin in Acidic γ-Valerolactone-H2O Pretreatment

Taming the Friedel–Crafts Reaction: Organocatalytic Approach to Optically Active 2,3‐Dihydrobenzofurans

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