Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• cyclohexanes and cyclopentanes, respectively. All the reactions leading to fused cyclohexanes (Table 3) increased tether strain in the transition structures, showing a negative contribution of the tether to the reactivity. The reaction of 1b has the lowest tether strain, because a decalin is formed. Relatively

• ) has a value lower than 10 kcal/mol being the main responsible of the lack of reactivity. Notably, in all cases, ΔE≠ti has a negative value indicating that both tethers have a synergic effect, although in any case it is not enough for favoring the reaction. In the case of fused cyclopentanes we

• cyclopentanes, with the exception of the highly constrained system 5-5. Considering the simplest bimolecular model 3, the fused cyclohexanes contribute with ca. 6–8 kcal/mol while the fused cyclopentanes contribute with ca. 15 kcal/mol (Table 5). Conclusion In conclusion, the computational topological study

Photoredox catalysis in nickel-catalyzed C–H functionalization

• Lusina Mantry,
• Rajaram Maayuri,
• Vikash Kumar and
• Parthasarathy Gandeepan

Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143

• , cyclopentanes, and n-pentane. The proposed catalytic cycle is initiated by the absorption of light by xanthone PC 21-I to get excited (Figure 21) [136]. The excited ketone PC undergoes a HAT process with the benzylic C–H substrate to generate a pair of ketyl radical 21-IV and benzylic radical 21-III. At the

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• system and the corresponding ROM product is shifted towards ROM because ring strain disfavors reclosing of the ring system. Therefore, functionalized norbornenes, which are highly strained scaffolds, easily provide a number of functionalized cyclopentanes across the ROM/CM process. It is well known that

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

α,γ-Dioxygenated amides via tandem Brook rearrangement/radical oxygenation reactions and their application to syntheses of γ-lactams

• Mikhail K. Klychnikov,
• Radek Pohl,
• Ivana Císařová and
• Ullrich Jahn

Beilstein J. Org. Chem. 2021, 17, 688–704, doi:10.3762/bjoc.17.58

• thermal radical cyclization reactions according to the persistent radical effect [79][80] forming functionalized cyclopentanes 6 (Scheme 1B). Based on this sequence various other reaction pathways can be envisaged. Among them we hypothesized that the nucleophilic ring opening of simple epoxides 7 by N

Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid

• Emeline Benoit,
• Ahmed Fnaiche and
• Alexandre Gagnon

Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113

• copper(II) triflate and Hünig's base, rearranges to give the corresponding 2-(arylthio)-3-alkyl-1,3-butadiene 10 [12]. Reacting methyl 2-phenylthiocyclopropyl ketone 11 with silyl enol ethers 12 in the presence of dimethylaluminium chloride leads to the functionalized cyclopentanes 13 via a highly

Studies towards the synthesis of hyperireflexolide A

• G. Hari Mangeswara Rao

Beilstein J. Org. Chem. 2018, 14, 2106–2111, doi:10.3762/bjoc.14.185

• antifungal [2] and cytotoxic activities [3]. γ-Lactone-fused cyclopentanes are of vital importance in organic synthesis and are the most abundant substructures found in various naturally occurring molecules [4][5]. A cis-cyclopentane ring-fused γ-lactone is the key structural unit of many complex and

• synthetic methods are reported to attain γ-lactone-fused cyclopentanes [25][26][27][28][29][30][31]. Earlier from our lab, we reported a short and efficient methodology for the synthesis of γ-lactone-fused cyclopentane 5 [32]. The cis-ring junction of this carbocylic ring system offers a high degree of

Synergistic chiral iminium and palladium catalysis: Highly regio- and enantioselective [3 + 2] annulation reaction of 2-vinylcyclopropanes with enals

• Haipan Zhu,
• Peile Du,
• Jianjun Li,
• Ziyang Liao,
• Guohua Liu,
• Hao Li and
• Wei Wang

Beilstein J. Org. Chem. 2016, 12, 1340–1347, doi:10.3762/bjoc.12.127

• outcomes were also received in DCE, ether, CH3CN and EtOAc (Table 2, entries 3–6). Gratifyingly, in CHCl3 this reaction proceeded smoothly to furnish the desired cyclopentanes in 63% yield with 99% ee for major 3a’ and 83% ee for minor 3a’’ with a dr ratio of 1.7:1 (Table 2, entry 7). The reaction

• further optimization of reaction conditions found that the addition of additional 0.5 equiv 1a into the reaction mixture in 4 portions significantly improved the reaction yield (83%, Table 2, entry 13). In order to improve the diastereoselectivity of this reaction, other cyclopentanes used in Trost’s

• ] annulation process by the variation of vinylcyclopropanes and enals (Table 3). The results exhibit that the synergistic catalyzed enantioselective [3 + 2] annulation process serves as a general approach to structurally chiral cyclopentanes bearing 3-consecutive stereogenic centers with high regio- and

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

• atom, in high yields and with up to 90% ee (Scheme 4) [37]. 3-Alkylideneindolin-2-ones underwent [3 + 2] annulations with allenoates, affording various biologically relevant spirocyclic oxindolic cyclopentanes in excellent yields and greater than 97% ee (Scheme 5) [38]. Enantioselective [3 + 2

The preparation of several 1,2,3,4,5-functionalized cyclopentane derivatives

• André S. Kelch,
• Peter G. Jones,
• Ina Dix and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 1705–1712, doi:10.3762/bjoc.9.195

• . In principle these should be convertible by elimination reactions to the desired target molecule. Keywords: bromination; cyclopentanes; esterification; permethylcyclopentadiene; polyfunctional compounds; radialenes; Introduction Radialenes are cyclic cross-conjugated hydrocarbons that consist

Inter- and intramolecular enantioselective carbolithiation reactions

• Asier Gómez-SanJuan,
• Nuria Sotomayor and
• Esther Lete

Beilstein J. Org. Chem. 2013, 9, 313–322, doi:10.3762/bjoc.9.36

• -butyllithium in the presence of (−)-sparteine (L1) at −78 °C giving trans-substituted cyclopentanes 29 in high diastereo- and enantioselectivity. The primary benzyllithium intermediates are also diastereoselectively substituted by different electrophiles creating a third consecutive stereogenic center (Scheme

N-Heterocyclic carbene/Brønsted acid cooperative catalysis as a powerful tool in organic synthesis

• Rob De Vreese and
• Matthias D’hooghe

Beilstein J. Org. Chem. 2012, 8, 398–402, doi:10.3762/bjoc.8.43

• -unsaturated aldehydes [18], the enantioselective synthesis of cyclopentenes from α,β-unsaturated aldehydes and α,β-unsaturated ketones [19], and the preparation of cyclopentanes through the reaction of enals and β,γ-unsaturated α-ketoesters [20]. Discussion Recently, Rovis et al. reported that the acetate

Synthesis of chiral cyclohexanes and carbasugars by 6-exo-dig radical cyclisation reactions

• Rajeev K. Shrivastava,
• Elise Maudru,
• Gurdial Singh,
• Richard H. Wightman and
• Keith M. Morgan

Beilstein J. Org. Chem. 2008, 4, No. 43, doi:10.3762/bjoc.4.43

• of carbohydrates as precursors for highly functionalised carbocyclic rings systems has found wide utility in organic synthesis [1][2][3][4][5][6][7][8][9][10][11]. In particular there is a large amount of literature devoted to the synthesis of cyclopentanes [12][13] that employs a 5-exo-dig ring