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

• compounds. As a result, this review describes the use of various eco-friendly greener protocols to synthesize N-substituted pyrroles. This synthesis involves the reaction of various aliphatic/aromatic primary amines, and sulfonyl primary amines with 2,5-dimethoxytetrahydrofuran in the presence of numerous

• proposed by Wang [55] (Scheme 2b), 2,5-dimethoxytetrahydrofuran (2) is first protonated with acetic acid, followed by ring opening to form carbocation B. In the following step, primary amine 1 nucleophilically attacks carbocation B to produce intermediate C, which, after proton rearrangement and the

• temeperatures. In 2000, the application of the Clauson–Kaas reaction was nicely explored by Sonnet et al. [56] for the preparation of diverse pyrrolizinones. The pyrrole derivatives 5 and 7 were synthesized by the classical Clauson–Kaas reaction by refluxing amines 4 or 6 with 2,5-dimethoxytetrahydrofuran (2

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• the same compound 6 from the triamine 4 utilizing a three-fold Clauson–Kaas reaction in the presence of 2,5-dimethoxytetrahydrofuran (10) under acetic acid reflux conditions (Scheme 3). Alternatively, the pyrrole-based system 6 has also been prepared starting from truxene (7) in three steps, involving

• , 137.70, 125.49, 119.39, 118.48, 114.03, 110.51, 110.33, 55.84, 36.76, 26.54, 22.83, 13.85; IR (KBr): 2953, 2922, 2855, 1962, 1608, 1497 cm−1; MS (m/z): 874.95. Method B: Triaminotruxene 4 (300 mg, 0.41 mmol) and 2,5-dimethoxytetrahydrofuran (10, 273.77 mg, 2.05 mmol) were dissolved in acetic acid (5 mL

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• –270 °C for 20 h, (e) after filtration, washing, and drying, MWCNTs-SO3H composite 97 was achieved (Scheme 17). N-Substituted pyrroles 99 were obtained in good to excellent yields (40–92%) via a simple and green reaction between 2,5-dimethoxytetrahydrofuran (98) and primary amines 15 in water media at

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• via a Clausson–Kaas protocol using 2,5-dimethoxytetrahydrofuran (DMTHF) as a source of succinic aldehyde (Scheme 3) [25]. The purity of the prepared compounds was confirmed by elemental analysis and NMR and IR spectroscopic data. Spectroscopic and luminescent properties of the synthesized compounds

First synthesis of meso-substituted pyrrolo[1,2-a]quinoxalinoporphyrins

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2014, 10, 808–813, doi:10.3762/bjoc.10.76

• -triphenylporphyrin. The reaction of this porphyrin with 2,5-dimethoxytetrahydrofuran, followed by the reduction of the nitro group in the presence of NiCl2/NaBH4 afforded 5-(3-amino-4-(pyrrol-1-yl)phenyl)-10,15,20-triphenylporphyrin. This triphenylporphyrin underwent a Pictet–Spengler cyclization after the reaction

• [1,2-a]quinoxalinoporphyrins (4a–h) is depicted in Scheme 1. At first, 5-(4-amino-3-nitrophenyl)-10,15,20-triphenylporphyrin (1) was synthesized from 5,10,15,20-tetraphenylporphyrin (TPP) after a series of reactions [46][49] in five steps. The Clauson–Kaas reaction of porphyrin (1) with 2,5

• -dimethoxytetrahydrofuran in toluene/acetic acid mixture afforded novel 5-(3-nitro-4-(pyrrol-1-yl)phenyl)-10,15,20-triphenylporphyrin (2) in 89% yield. The reduction of nitroporphyrin 2 was initially carried out by using Sn/HCl, SnCl2·2H2O/HCl, and Pd/C–NaBH4 as reducing agents but the reaction was found to be sluggish and