Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• confirmed that the cyclization pathways were controlled by the influence of substituents on the stability of the intermediates. This work expanded the scope of gold-catalyzed reactions through systematic cycloisomerization studies of 1,6-enynes and an ethyl 4-oxocyclohexanecarboxylate-derived 1,7-enyne. In

• products and pharmaceutical agents. In 2013, Chan and co-workers reported a ligand-controlled cycloisomerization of 1,7-enyne esters affording the selective synthesis of cis-tetrahydropyridinones and δ-diketones (Scheme 16) [24]. When NHC-ligated gold catalysts were employed, a cascade sequence comprising

• intermediate 76 to drive hydrolysis. This methodology tolerates structurally diverse 1,7-enyne esters and generates defined cis-1,2,3,6-tetrahydropyridine scaffolds, which serve as synthetic intermediates for complex natural products and pharmacologically relevant heterocyclic frameworks. In 2016, Jiang group

Mechanisms for radical reactions initiating from N-hydroxyphthalimide esters

• Carlos R. Azpilcueta-Nicolas and
• Jean-Philip Lumb

Beilstein J. Org. Chem. 2024, 20, 346–378, doi:10.3762/bjoc.20.35

• conditions, affording product 61 [60]. On the other hand, reaction with 1,7-enyne 62 affords dihydroquinolinone product 63 via a cascade radical addition/cyclization process [61]. In both transformations, HE serves a dual role by activating the NHPI ester through EDA complex formation and providing a

Synthetic study toward the diterpenoid aberrarone

• Liang Shi,
• Zhiyu Gao,
• Yiqing Li,
• Yuanhao Dai,
• Yu Liu,
• Lili Shi and
• Hong-Dong Hao

Beilstein J. Org. Chem. 2022, 18, 1625–1628, doi:10.3762/bjoc.18.173

• functional transformation from 10, which itself would be prepared through methylation and conjugate addition from Pauson–Khand adduct 11. This cyclopentenone could be readily accessed from 1,7-enyne 12 which could be obtained through the reported procedure [35] from the commercially available 5-hexenoic acid

Pauson–Khand reaction of fluorinated compounds

• Jorge Escorihuela,
• Daniel M. Sedgwick,
• Alberto Llobat,
• Mercedes Medio-Simón,
• Pablo Barrio and
• Santos Fustero

Beilstein J. Org. Chem. 2020, 16, 1662–1682, doi:10.3762/bjoc.16.138

• )8 followed by the addition of NMO), and starting from the pure anti diastereoisomer of 1,7-enyne 20, the expected bicyclic enone was obtained in good yield and high diastereoselectivity (de > 95%). An attempt to extend the PKR to the formation of a fused tricyclic structure, starting from 1,7-enyne

• ring-fused cyclopentenone 25d in both lower yield (53%) and lower diastereoselectivity. A catalytic PKR of fluorinated 1,7-enyne amides 26 using catalytic amounts of [Rh(COD)Cl]2 was reported in 2008 by Hammond and co-workers [52]. The authors concluded that the reaction was highly sensitive to

• PKR of chiral N-tethered 1,7-enyne bearing a vinyl fluoride [64]. Catalytic intramolecular PKR of chiral N-tethered 1,7-enynes [64]. Model fluorinated alkynes used by Riera and Fustero [70]. PKR with norbornadiene and fluorinated alkynes 58 [71]. Nucleophilic addition/detrifluoromethylation and retro

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• (trifluoromethyl)thiyl radical, which added onto the double bond of 17.1a–d, and finally delivered the desired products 17.5a–d in good yields, through the intermediacy of radicals 17.3·a–d and iminyl radicals 17.4·a–d [85]. The double bond of acrylamides embedded into a 1,7-enyne framework likewise allowed the

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• the alkene moiety of the 1,7-enyne, two consecutive cyclizations lead to the final sulfonylated benzo[α]fluoren-5-one. Electron and proton transfer and subsequent formation of dihydrogen close the catalytic cycle and regenerate the photocatalyst. Sulfinamides Formation of sulfoxides A new method for

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• alcohols revealed a matched/mismatched effect that was strongly dependent on the nature of the solvent. Keywords: asymmetric catalysis; [3.1.0] bicycles; [4.1.0] bicycles; cycloisomerization; 1,6-enyne; 1,7-enyne; ruthenium catalysis; sulfoxide; Introduction Due to their prevalence in natural products [1

• substitution reactions [42] (Figure 1b), would be able to impart sufficiently useful enantioselectivities on these complex, drug-like molecules. While the idea certainly was appealing at first glance, this reaction is complicated by the fact that the 1,6- and 1,7-enyne substrates contain a stereogenic center

• decided to initiate our efforts on 1,7-enyne sulfonamide 13 for reaction optimization. Table 1 showcases our initial experiments. With 3 mol % of CpRu-sulfoxide catalyst 1 in THF at 40 °C, 14 could be obtained in a 69% yield and a promising 26.5:73.5 er (Table 1, entry 1). This important first experiment

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• /AgClO4] (5/15 mol %) furnished corresponding functionalized pyrrolidines in good yields and moderate stereoselectivity (Scheme 22) [58]. The preferred alkene activation versus allenes was recently observed in the cascade 1,3-migration/[2 + 2] cycloaddition of 1,7-enyne benzoates (Scheme 23) [59]. When 83

• with simple ketones. Proposed reaction mechanism for the intramolecular [Au(I)]-catalyzed hydroalkylation of alkenes with ketones. Tandem Michael addition/hydroalkylation catalyzed by [Au(I)] and [Ag(I)] salts. Intramolecular [Au(I)]-catalyzed tandem migration/[2 + 2] cycloaddition of 1,7-enyne

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• , underwent nucleophilic attack by the cyclopropene in a 5-exo-dig manner followed by ring-opening. A subsequent Friedel–Crafts cyclization allowed the formation of the indene subunit (Equation 1, Scheme 32). Sulfonamide 91 contains a 1,7-enyne subunit and its gold-catalyzed cycloisomerization delivered

Synthesis of fluorinated δ-lactams via cycloisomerization of gem-difluoropropargyl amides

• Satoru Arimitsu and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2010, 6, No. 48, doi:10.3762/bjoc.6.48

• Satoru Arimitsu Gerald B. Hammond Department of Chemistry, Kyoto University, Kyoto, Japan Department of Chemistry, University of Louisville, Louisville, Kentucky 40292, United States 10.3762/bjoc.6.48 Abstract gem-Difluoro-1,7-enyne amides are suitable building blocks for the synthesis of

• by a tandem metathesis reaction, this would permit the synthesis of multi-substituted gem-difluoroisoquinolinones through a subsequent Diels–Alder reaction (eq 2, Scheme 2) [28]. In this regard, we screened various ruthenium carbene complexes using 1,7-enyne amide 1a and styrene 8a as a model

• (Scheme 3). In summary, gem-difluoro-1,7-enyne carbonyl derivatives are useful reaction partners in enyne metathesis cycloisomerization and CM–EYM tandem reactions catalyzed by ruthenium carbene complexes. The resulting diene products can be elaborated further using a Diels–Alder reaction. Comparison of