A Diels–Alder probe for discovery of natural products containing furan moieties

• Alyssa S. Eggly,
• Namuunzul Otgontseren,
• Carson B. Roberts,
• Amir Y. Alwali,
• Haylie E. Hennigan and
• Elizabeth I. Parkinson

Beilstein J. Org. Chem. 2024, 20, 1001–1010, doi:10.3762/bjoc.20.88

• the titers of MMFs in native producing strains. However, if titers are similar to that of γ-butyrolactones and butenolides quorum sensing molecules, we would expect them to be between 80 and 2.5 nM [29][30][31]. Given these very low concentrations, cultures would need to be greatly concentrated (≈1000

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides

• Alexander Yanovich,
• Anastasia Vepreva,
• Ksenia Malkova,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48

• ) or a bromine atom. These transformations yield spiro-annulated O-heterocycles with succinimide ring, namely spiro-Δα,β-butenolides 2 and 3, tetrahydrofurans 4 and benzopyrans 5 (Scheme 1). Fragments of these oxygen-containing spiro-conjugated heterocycles are part of many important drugs and natural

• products. For example, spirocyclic Δα,β-butenolides (furan-2(5H)-ones) represent a valuable class of molecular frameworks for drug design and are abundant in nature [15]. Bioactive naturally occurring spiro Δα,β-butenolides include spirofragilide (with anti-inflammatory, antibiotic, antitumor, anti-HIV

• activity) [16], ramariolide A (antitubercular) [17], (+)-massarinolin A (antibacterial) [18], anemonin (antiparasitic) [19], (+)-pyrenolide D (cytotoxic) [20], and (+)-crassalactone D (antitumor) [21]. Synthetic or semisynthetic spiro Δα,β-butenolides have also shown a range of biological properties

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• according to the different positions of the OMe group. The preparation of α,α-bisthiofunctionalized butenolides through a bis-sulfenylation methodology was reported by Zhou and Yuan et al. [49]. For this purpose, they applied N-(alkyl(aryl)sulfanyl)succinimides or N-(phenylsulfanyl)phthalimides using a

Synthesis of sulfur karrikin bioisosteres as potential neuroprotectives

• Martin Pošta,
• Václav Zima,
• Lenka Poštová Slavětínská,
• Marika Matoušová and
• Petr Beier

Beilstein J. Org. Chem. 2022, 18, 549–554, doi:10.3762/bjoc.18.57

• ; butenolides; karrikin; sulfur; Introduction Neurological disorders, especially the Alzheimer’s and the Parkinson’s diseases represent a serious problem for elderly populations worldwide. Studies of these neurodegenerative diseases led to the discovery of a deficit of acetylcholine and dopamine levels in the

• Goddard-Borger [24] for the preparation of 2 using the Xavier’s procedure [33] towards 5-thiopyranose-fused butenolides and the reaction pathway is outlined in Scheme 5. The synthesis of the key intermediate butenolide 23 was accomplished starting from easily available ᴅ-xylose, following a published

1,5-Phosphonium betaines from N-triflylpropiolamides, triphenylphosphane, and active methylene compounds

• Vito A. Fiore,
• Chiara Freisler and
• Gerhard Maas

Beilstein J. Org. Chem. 2019, 15, 2603–2611, doi:10.3762/bjoc.15.253

• leading to butenolides occurs easily [17]. In contrast to acetylenic esters and ketones, acetylenic carboxamides have rarely been exposed to nucleophilic phosphanes in organocatalytic or stoichiometric reactions. Recently, we have reported on the synthesis and reactivity of N-triflylpropiolamides 1

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• for the generation of carbon radicals via single-electron transfer (SET). In 2016, Barriault and co-workers reported a methodology that features the utilization of dimeric gold complex [Au2(dppm)2]Cl2 and ultraviolet A (UV, 365 nm) light to direct arylation of bromide-substituted butenolides or cyclic

Synthesis of chiral 3-substituted 3-amino-2-oxindoles through enantioselective catalytic nucleophilic additions to isatin imines

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 1349–1369, doi:10.3762/bjoc.14.114

• -bromo-substituted derivative (R2 = 5-Br) which afforded the corresponding product in only 41% ee. An advantage of this methodology was the use of a very low catalyst loading (1 mol %). Earlier in 2016, Silvani and Lesma described the synthesis of chiral 3-amino-2-oxindole butenolides 11 on the basis of

• an enantioselective organocatalytic Mannich reaction between isatin-derived benzhydrylketimines 12 and trimethylsiloxyfuran 13 [38]. Using 10 mol % of another type of organocatalyst, such as chiral phosphoric acid 14, the process led at −40 °C in THF to the corresponding butenolides 11 in moderate to

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• prepared from the corresponding allylic alcohol 63 by esterification with the anhydride 64 derived from cyclobutene. Later, the ester 65, on treatment with the catalyst 1 under toluene reflux conditions followed by treatment with the catalyst 2 furnished the macrolide-butenolides 66 in 42–48% yields via

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5

• Ulrike Groenhagen,
• Michael Maczka,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2014, 10, 1421–1432, doi:10.3762/bjoc.10.146

• and their biosynthesis seems tightly connected to the biosynthesis of streptazolin. A similar case has been reported for specific volatile butenolides released by streptomycetes producing the antibiotic antimycin [33] and for other strains investigated by us. The analysis of volatiles and detection of

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

The regulation and biosynthesis of antimycins

• Ryan F. Seipke and
• Matthew I. Hutchings

Beilstein J. Org. Chem. 2013, 9, 2556–2563, doi:10.3762/bjoc.9.290

• -formamidosalicylic acid moiety and they comprise more than 40 known members (Figure 1) [15][16][17][18][19][20][21][22]. Antimycins can undergo base-catalysed decomposition resulting in the production of volatile blastmycinones and butenolides [23]. The main mode of action of antimycins is to inhibit cytochrome c

Tandem aldehyde–alkyne–amine coupling/cycloisomerization: A new synthesis of coumarins

• Maddi Sridhar Reddy,
• Nuligonda Thirupathi and
• Madala Haribabu

Beilstein J. Org. Chem. 2013, 9, 180–184, doi:10.3762/bjoc.9.21

• aminoindolizines, 2-(aminomethyl)indoles, imidazopyridines, butenolides and 1,2-dihydroisoquinoline derivatives, respectively, combining these two approaches successfully. Along the same lines, we investigated a reaction between ethoxyacetylene, pyrrolidine and salicylaldehyde in the presence of a transition-metal

Algicidal lactones from the marine Roseobacter clade bacterium Ruegeria pomeroyi

• Ramona Riclea,
• Julia Gleitzmann,
• Hilke Bruns,
• Corina Junker,
• Barbara Schulz and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2012, 8, 941–950, doi:10.3762/bjoc.8.106

• ), 990 (w), 930 (m), 810 (w), 657 (w) cm−1; UV–vis: λmax (log ε): 228 (2.83) nm. General procedure for the ring-closing metathesis to butenolides: Grubbs catalyst of the second generation (0.05 equiv) was added to a solution of the ester 15 or 16 (1.0 equiv) in dry dichloromethane (0.05 M). The mixture

• was stirred under reflux for 5 d. The solvent was removed under reduced pressure and the residue was purified by column chromatography on silica gel (pentane/diethyl ether 3:1) to give the butenolides as colourless oils. 2-Methylpent-2-en-4-olide (11): Yield: 0.48 g (3.96 mmol, 85%). TLC (hexane/ethyl

• ), 1086 (s), 1047 (m), 1022 (m), 959 (m), 856 (m), 786 (m), 761 (w), 612 (w), 555 (w) cm−1; UV–vis λmax (log ε): 229 (2.83) nm. NMR spectroscopic data are in agreement with previously published data [32]. General procedure for the catalytic hydrogenation of butenolides: To a solution of the lactone 11 or

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• for the preparation of substituted butenolides 101 and isocoumarins [51]. In this study, the authors employed a carbophilic Lewis acidic Au(I) catalyst to catalyze the cross-coupling reactivity of a second Lewis basic Pd catalyst in order to functionalize vinyl–gold intermediates arising from

• ). Similar strategies [145][146] were applied to synthesize arylated (Z)-enones, -enals or dihydrocyclohepta[b]indole skeletons 277 by gold-catalyzed cascade Friedel–Crafts/furan (or indole)–alkyne cycloisomerizations (Scheme 48). The polysubstituted butenolides 281 could be obtained through a gold-catalyzed

• products were constructed through a formal [2 + 2 + 1] cycloaddition that involved α-carbonyl–carbenoids, nitroso species and external alkenes (Scheme 58). A gold(I)-catalyzed cascade cyclization/oxidative cross-coupling process has been devised to prepare β-alkynyl-γ-butenolides 366 directly from