Figure - uploaded by Bina S Siddiqui
Content may be subject to copyright.
Scheme 2 Synthesis of an aryl bromide functionalised precursor to dihydrodehydrodiconiferyl alcohol. Reagents and conditions: (a) KH, 18-crown-6, THF, 60 • C, 1.5 h (98%); (b) n BuLi, (methoxymethyl) triphenylphosphonium chloride, THF,-78 • C→rt, 5 h (70%); (c) Hg(OAc) 2 , MeCN-H 2 O, rt, 1 h (67%); (d) NaClO 2 , 2-methyl-2-butene, NaH 2 PO 4 ·2H 2 O, t BuOH-H 2 O, 0 • C→rt then rt, 14 h (86%); (e) CH 2 N 2 , Et 2 O-THF,-78 • C→rt (95%); (f) p-ABSA, DBU, MeCN, 0 • C→rt then rt, 24 h (90%); (g) Rh 2 [S-DOSP] 4 (1.3 mol%), toluene, 0 • C, 2 h (95%); (h) NaOMe, MeOH,-60 • C, 26 h (96%).
Source publication
Structural revision of lawsonicin, a natural product of Lawsonia alba, is reported based upon comparison of its spectral data with that of the naturally occurring dihydrobenzo[b]furan neolignan (rac)-trans-dihydrodehydrodiconiferyl alcohol, which is found to be identical. A concise synthesis of dihydrodehydrodiconiferyl alcohol, via Rh(2)[S-DOSP](4...
Citations
... 31,32 However, most previously reported methods for the synthesis of ketones have employed secondary alcohols, rather than primary alcohols, even though primary alcohols have been widely utilized in many organic syntheses and are also found in a large number of useful molecules such as natural products, pharmaceuticals, and materials. 33,34 To the best of our knowledge, utilization of primary alcohols to prepare ketones has not been extensively studied. Moreover, previously reported reactions using primary alcohols required harsh reaction conditions. ...
A practical one-pot synthesis of ketones from primary alcohols is described. Primary alcohols were successfully transformedviatreatment with dibromoisocyanuric acid and various aromatic compounds in the presence of Fe2O3to give ketone compounds. This reaction protocol provides an efficient and useful approach to the synthesis of various aromatic ketones from primary alcohols in high yields under mild reaction conditions. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021.
... 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). ...
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.
... Louis, MO, USA). A standard sample of ( ± ) dihydrodehydrodiconiferyl alcohol (3, see Fig. 1) was isolated in our laboratory from aerial parts of L. orientalis, and identified by comparison of its spectral (UV, 1 H NMR, 600.20 MHz) data with those found in the literature (Shen et al., 1998;Meng et al., 2010). The compound 3 was of purity 90.0% (by HPLC). ...
... The known compounds were identified by comparison of their 1 H NMR data with those previously reported (Kisiel, 1992;Pieters et al., 1990;Meng et al., 2010;Moyroud and Strazewski, 1999;Ushiyama and Furuya, 1989;Takeda et al., 1998). ...
Lactuca orientalis, hitherto phytochemically unexamined plant, has been used as a food or forage plant in some countries of the Near East. Six neolignans – derivatives of dihydrodehydrodiconiferyl alcohol, one sesquiterpene lactone – leucodin, one apocarotenoide – loliolide, and two simple phenolic compounds – vanilin and methyl 4-hydroxybenzoate were isolated from roots and aerial parts of the plant. Three of the isolated neolignans, i.e. 4-O-methyldihydrodehydrodiconiferyl alcohol and its two glucosides, were found for the first time in the genus Lactuca. Moreover, presence of dihydroconiferin, nucleosides (adenosine and uridine) and caffeic acid derivatives was revealed in the plant material using combined chromatographic and spectroscopic (¹H NMR) techniques. Major phenolic constituents of young shoots and leaves, i.e.: caffeic acid derivatives (caftaric acid, chlorogenic acid, caffeic acid and cichoric acid), dihydroconiferin and neolignans (dihydrodehydrodiconiferyl alcohol, 4-O-methyldihydrodehydrodiconiferyl alcohol), were quantified. Cichoric acid (c. 0.66% dry weight) and dihydrodehydrodiconiferyl alcohol (c. 0.76% dry weight) were the most abundant phenolic compounds detected in the examined tissue.
... The six compounds (Figure 1) isolated in the present studies were identified as lawsowaseem (1) [8], lawsonic acid (2) [7], vomifoliol (3) [9], lawsonicin (4) [6,10], lawsonin (5) [7] and lawsonadeem (6) [6] by comparing their spectral data with those reported in the literature. ...
The antituberculosis activity of six constituents including three triterpenoids, lawsowaseem, lawsonic acid, lawsonin; a dihydrobenzofuran derivative, lawsonicin; a naphthoquinone derivative, lawsonadeem, and vomifoliol isolated from the aerial parts of Lawsonia alba Lam was investigated. Compounds were identified using spectroscopic analysis. All the compounds were tested for their antitubercular activity against Mycobacterium tuberculosis strain H37 Rv and showed growth inhibition from 0 to 60 % at 6.25 µg/mL. Two acetyl derivatives were also assayed and caused 100 and 72 % growth inhibition of Mycobacterium tuberculosis strain H37 Rv respectively at MIC 6.25 µg/mL in the primary screen.
Comprehensive Summary
A highly enantioselective palladium‐catalyzed intramolecular Heck reaction of unactivated alkenes is developed, which provides a powerful route to access a broad range of chiral 3,3‐disubstituted‐2,3‐dihydrobenzofurans bearing all‐carbon quaternary stereocenter of interest in pharmaceutical research. Its salient features include high yield, excellent chemo‐ and enantioselectivity, mild conditions, a broad substrate scope as well as versatile transformations of the product.
Squaramide/cinchona alkaloid-derived bifunctional organocatalysts are in high demand in asymmetric transformations. Bifunctional quinine-derived sterically encumbered squaramide (H-bond donor) organocatalysts were used to catalyze the asymmetric Friedel-Crafts/SN2 type domino reaction of (Z)-α-bromonitroalkenes and α/β-naphthols and phenol derivatives to generate enantiomerically enriched dihydronaphthofuran (DHN) and dihydrobenzofuran (DHB) derivatives, respectively. The target adducts were obtained in up to >99% ee under mild conditions with a relatively low catalyst loading (5 mol%) compared to the methods known in the literature. In addition, density functional theory (DFT) calculations were performed to establish a possible outcome, explaining the origin of the stereoselectivity. It was discovered that π-stacked interactions for the trans-conformation in the Friedel-Crafts step are 0.79 kcal mol-1 more stable than the cis-conformation.
We have developed an efficient protocol for the construction of polycyclic dihydrobenzofuran spirooxindole scaffolds via base promoted cascade annulation of Morita-Baylis-Hillman (MBH) carbonates of isatins with ortho-hydroxychalcones or ortho-hydroxy-β-nitrostyrenes. The complex polycyclic compounds were conveniently synthesized in satisfactory yields and with high diastereoselectivity. This protocol provides a swift and convenient approach for the assembly of diverse highly functionalized dihydrobenzofuran spirooxindoles and also features broad substrate scope, high molecular convergence, and excellent atomic economy.
A dual nickel-/palladium-catalyzed gem-difluorovinylation of alkynyl bromoarenes is presented. This method proceeds smoothly to afford various dihydrobenzofuran compounds containing gem-difluorovinyl fragments with excellent stere-oselectivities in moderate to excellent yields. This...
In this work, we present a strategy for the preparation of functionalized 2,3-dihydrobenzofuran derivatives via the Cs2CO3-catalyzed domino annulation of enantiopure chiral salicyl N-phosphonyl imines with bromo malonates, which offers an avenue for the construction of 2,3-dihydrobenzofurans. Nineteen examples were synthesized in impressive chemical yields and diastereoselectivity. The products were purified simply by washing the crude mixtures with hexanes following group-assisted purification chemistry/technology to bypass traditional separation methods which often result in a loss of product. The absolute configuration was unambiguously assigned by X-ray structural analysis.
