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

• synthesis; 1,n-enynes; pathway economy; small-molecule skeletons; Introduction As organic synthesis concepts continue to evolve, economical synthesis remains a foundational principle for synthetic chemists [1][2][3][4][5][6][7]. The essence of economical synthesis lies in the conservation of materials and

• systematically regulating reaction parameters (solvent, substituent, ligand, catalyst) in 1,n-enyne cyclizations, enabling efficient "one-to-many" transformations that drastically reduce synthetic steps and resource consumption. Review Solvent-controlled cyclization of 1,n-enynes Solvents play a multifaceted

• radical initiated intramolecular cascade cyclization of 1,n-enynes to provide structurally diverse heterocycles (Scheme 4) [11]. Solvent selection dictated divergent reaction pathways under I2/TBHP oxidation. When an acetonitrile/water mixed solvent was used, iodine radical addition to the alkyne

Electrochemical cyclization of alkynes to construct five-membered nitrogen-heterocyclic rings

• Lifen Peng,
• Ting Wang,
• Zhiwen Yuan,
• Bin Li,
• Zilong Tang,
• Xirong Liu,
• Hui Li,
• Guofang Jiang,
• Chunling Zeng,
• Henry N. C. Wong and
• Xiao-Shui Peng

Beilstein J. Org. Chem. 2025, 21, 2173–2201, doi:10.3762/bjoc.21.166

• synthesis of cyclic compounds have emerged. The electrochemical functionalization of alkynes was highlighted by Ahmed in 2019 [109], Zhang described radical annulation of 1,n-enynes under photo/electrochemical reaction conditions in 2023 [110], the electrochemical formation of heterocycles was summarized by

Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents

• Jiangfei Chen,
• Yi-Lin Qu,
• Ming Yuan,
• Xiang-Mei Wu,
• Heng-Pei Jiang,
• Ying Fu and
• Shengrong Guo

Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98

• intermediate 12. Subsequent intramolecular cyclization and oxidative aromatization lead to the final isoxazoline-featured oxindole 9. In 2017, Li’s group reported an oxidative divergent bicyclization of 1,n-enynes through α-C(sp3)–H functionalization of alkyl nitriles using a Sc(OTf)3 and Ag2O system (Scheme 7

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

• of fluorine-containing compounds The utility of the Pauson–Khand reaction in the preparation of polycyclic compounds bearing both nitrogenated and cyclopentenone rings, two ubiquitous domains in drugs and natural products, has been reported in various contributions using 1,n-enynes, particularly 4

• -aza-1,7-enynes as starting materials [43][44][45]. However, the synthesis of fluorinated 1,n-enynes as well as the corresponding Pauson–Khand adducts has, until recently, scarcely been described in the literature. The intramolecular version of this reaction has recently gained recognition since it

• imine-derived CF3-containing enyne, bearing the trifluoromethylethynyl group at the ortho position (Scheme 16) [55]. One of the key steps in the preparation of the starting 1,n-enynes was a highly diastereoselective allylation reaction of chiral Ellman’s sulfinylimines. Based on this strategy, chiral

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• . Protonation and isomerization generate cobalt complex G4, which is converted into alkenated product 54 by ligand exchange. 4. Hydroarylation of enynes Catalytic cyclization of 1,n-enynes has become as an attractive tool for the preparation of cyclic adducts with a variety of functionalities in a one-pot

• process [92]. As the cyclization of 1,n-enynes with organometallics is well-known, the addition of an inert C–H bond to 1,n-enynes further enhances the economy of cyclization process. Thus, Cheng and co-workers reported a cobalt-catalyzed hydroarylative cyclization of 1,n-enynes with carbonyl compounds 55

Asymmetric Au-catalyzed cycloisomerization of 1,6-enynes: An entry to bicyclo[4.1.0]heptene

• Alexandre Pradal,
• Chung-Meng Chao,
• Patrick Y. Toullec and
• Véronique Michelet

Beilstein J. Org. Chem. 2011, 7, 1021–1029, doi:10.3762/bjoc.7.116

• , was reported in moderate to good yields and in enantiomeric excesses up to 99%. Keywords: asymmetric catalysis; bicycloheptene; cycloisomerization reactions; enynes; gold; Introduction Metal-catalyzed cycloisomerization reactions of 1,n-enynes have emerged as efficient processes that contribute to

• -enynes has been recently a field of high interest considering the fundamental skeleton rearrangement research of 1,n-enynes [1][2][3][4][5][6][7][8][9][10][11] and the potential applications in biological active and natural products [12][13]. In 1995, Blum et al. described a novel PtCl4-catalyzed