Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins

• Chandra Sekhar Tekuri,
• Pargat Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89

• -diamino-5,10,15,20-tetra(p-tolyl)porphyrin (1) with 2-hydroxynaphthalene-1,4-dione, dimedone and benzaldehyde in the presence of different acidic catalysts such as p-toluenesulfonic acid (PTSA), La(OTf)3, ʟ-ascorbic acid, p-dodecylbenzenesulfonic acid (DBSA), trichloroacetic acid (TCA) and trifluoroacetic

• acid (TFA) in CHCl3 for 3 hours at 65 °C under one-pot operation (Table 1, entries 1–6). Surprisingly, the reaction did not proceed when La(OTf)3 and ʟ-ascorbic acid were used as acidic catalysts (Table 1, entries 2 and 3). In contrast, the use of Brønsted acidic catalysts such as DBSA and PTSA

Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach

• Dileep Kumar Singh and
• Rajesh Kumar

Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71

• excellent yields. To obtain the best reaction conditions, various Lewis acid catalysts (e.g., FeCl3 CuCl2, InCl3, Cu(OTf)2, Mg(OTf)2, Zn(OTf)2, Yb(OTf)3, Y(OTf)3, Bi(OTf)3, La(OTf)3 and Sc(OTf)3), different solvents (e.g., CH2Cl2, CHCl3, CH3CN, CH3NO2, n-hexane, and dioxane), temperatures (90–110 °C), and

An efficient metal-free and catalyst-free C–S/C–O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

• Shubham Sharma,
• Dharmender Singh,
• Sunit Kumar,
• Vaishali,
• Rahul Jamra,
• Naveen Banyal,
• Deepika,
• Chandi C. Malakar and
• Virender Singh

Beilstein J. Org. Chem. 2023, 19, 231–244, doi:10.3762/bjoc.19.22

• indicated the superiority of DMF over other solvents. Subsequently, we examined the effects of La(OTf)3 as a catalyst in combination with DMF as a solvent. However, the targeted prototype 1C was obtained only in 20% yield at 60 °C after 24 hours of reaction time (entries 11 and 12, Table 1). Next, ZnO

Enantioselective PCCP Brønsted acid-catalyzed aza-Piancatelli rearrangement

• Gabrielle R. Hammersley,
• Meghan F. Nichol,
• Helena C. Steffens,
• Jose M. Delgado,
• Gesine K. Veits and
• Javier Read de Alaniz

Beilstein J. Org. Chem. 2019, 15, 1569–1574, doi:10.3762/bjoc.15.160

• facilitating this reaction has been extended to include other Brønsted and Lewis acids, such as phosphomolybdic acid (PMA) [24], Ca(NTf2)2 [25], In(OTf)3 [26], La(OTf)3 [27], and BF3·OEt2 [28], as well as other nucleophiles [29][30][31]. In all cases examined, the products of the aza-Piancatelli reaction have

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

• are not cleaved in 5–50% aqueous H2SO4 but on the contrary, these compounds are produced under these conditions. More efficient catalysts are the compounds Sn(OTf)2 and La(OTf)3 which can be used for the transformation of 2-hydroperoxy-2,4,4-trimethylpentane (172) into neopentyl alcohol (173) and

• acetone (171). The Sn(OTf)2 and La(OTf)3-catalyzed reaction afforded neopentyl alcohol (173) in 62 and 70% yield, respectively [320]. The hydrogen peroxide promoted ring expansion for the synthesis of oxabicycles 176a–c was described for the first time in 1985 [321]. The reaction involved the solvolysis

Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes

• M. Emin Cinar,
• Bernward Engelen,
• Martin Panthöfer,
• Hans-Jörg Deiseroth,
• Jens Schlirf and
• Michael Schmittel

Beilstein J. Org. Chem. 2016, 12, 813–824, doi:10.3762/bjoc.12.80

• (Scheme 2, Table 1). Aside of the ions mentioned in Table 1 the metal-mediated domino aldol reaction was also probed with LaCl3, La(OTf)3, CeCl3, Sc(OTf)3, BF3 and SnCl2 resulting in failure. While SnCl2 afforded 6a in 90% yield, LaCl3, La(OTf)3, CeCl3, and Sc(OTf)3 furnished 6a in 25, 52, 10 and 55

Synthesis of meso-substituted dihydro-1,3-oxazinoporphyrins

• Satyasheel Sharma and
• Mahendra Nath

Beilstein J. Org. Chem. 2013, 9, 496–502, doi:10.3762/bjoc.9.53

• -oxazine ring system were successfully synthesized from 5-(4-aminophenyl)-10,15,20-triphenylporphyrin in good yields. The structures of the target products were established on the basis of spectral data and elemental analyses. Keywords: dihydro-1,3-oxazinoporphyrins; iminoporphyrins; La(OTf)3; Mannich

• -triphenylporphyrin using SnCl2 under acidic conditions [41][42]. Firstly, meso-(4-aminophenyl)porphyrin 1 was reacted with salicylaldehyde or 5-chlorosalicylaldehyde in the presence of La(OTf)3 as a Lewis acid catalyst in toluene under reflux to afford the corresponding iminoporphyrins 2 and 3, which on reduction by

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• catalytic FC benzylations using benzyl alcohols have been developed. These utilize for instance Cl2Si(OTf)2, Hf(OTf)4 [8], Yb(OTf)3, La(OTf)3 [9], InCl3 [10][11], NbCl5 [12], heterobimetallic Ir-Sn-catalysts [13][14], H-mont [15], [CpMoCl(CO)3]/o-chloranil [16], strong Brønsted acids [17][18][19] calix[6