Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles

• Periklis X. Kolagkis,
• Eirini M. Galathri and
• Christoforos G. Kokotos

Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36

• of strong acidic sites that are on the carbon-based solid acids enhance their catalytic ability, compared to traditional Lewis and protic acids [41][42][43]. The most common examples in literature for the reaction of the synthesis of BIMs under solvent-free conditions utilize either protic acids

Selective synthesis of thioethers in the presence of a transition-metal-free solid Lewis acid

• Federica Santoro,
• Matteo Mariani,
• Federica Zaccheria,
• Rinaldo Psaro and
• Nicoletta Ravasio

Beilstein J. Org. Chem. 2016, 12, 2627–2635, doi:10.3762/bjoc.12.259

• substrates under mild reaction conditions. Keywords: no solvent; S-alkylation; solid acids; thioethers; transition-metal-free; Introduction The need for more sustainable processes in the fine chemical industry is growing continuously. An optimal use of resources, both energy and starting materials, and a

• report that excellent yields can be obtained in the presence of an amorphous solid catalyst under solvent-free conditions. Results and Discussion In order to test our hypothesis we carried out the reaction of 1-(4-methoxyphenyl)ethanol (1a) and benzyl mercaptan (2a) in the presence of different solid

• acids, namely 13% Al2O3 on silica (SiAl 13), 4.7% ZrO2 on silica (SiZr 4.7), 2.3% TiO2 on silica (SiTi 2.3) and 0.6% Al2O3 on silica (SiAl 0.6) whose textural properties are summed up in Supporting Information File 1, Table S1. Results are reported in Table 1. It is worth underlining that under these

Diels–Alder reactions in confined spaces: the influence of catalyst structure and the nature of active sites for the retro-Diels–Alder reaction

• Ángel Cantín,
• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2016, 12, 2181–2188, doi:10.3762/bjoc.12.208

• reversibility of the reaction, homogeneous Lewis acids [1][2][3][4], solid acids [5][6] as catalyst, high pressures [6][7][8] and/or water as a solvent [9][10] have been reported. In particular, and among the most interesting environmental-friendly reactions, the cycloaddition reaction occurs with high

Silica-supported sulfonic acids as recyclable catalyst for esterification of levulinic acid with stoichiometric amounts of alcohols

• Raimondo Maggi,
• N. Raveendran Shiju,
• Veronica Santacroce,
• Giovanni Maestri,
• Franca Bigi and
• Gadi Rothenberg

Beilstein J. Org. Chem. 2016, 12, 2173–2180, doi:10.3762/bjoc.12.207

• free, 75 °C, 2 h. Synthesis of levulinic acid from ligno-cellulosic feedstocks and its principal uses to access fine chemicals. Screening of different solid acids in the esterification reaction of levulinic acid with 1-pentanol. Variation of the acid/alcohol ratio. Variation of the reaction temperature

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• , separation and purification drawbacks, and production of waste. As already mentioned in the previous paragraph, practical solutions to such problems are offered by using solid acids, although these systems may suffer from mass-transfer limitations causing low activity, and consequently, extended reaction

• inorganic or solid acids and bases. Advantages in this case are mainly the recovery and recyclability of the catalyst system and the improved selectivity that is often achievable. Secondly, the here presented reactions have a common mechanistic feature based on the cooperative nucleophilic–electrophilic

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

• in the Baeyer–Villiger reaction with increasing frequency. Various catalysts that activate hydrogen peroxide, such as heterogeneous catalysts based on solid acids [201], zeolites [202][203], Se [204], As [205], Co [206], sulfonated organic ion exchange resins [203][207], and homogeneous catalysts

Continuous flow nitration in miniaturized devices

• Amol A. Kulkarni

Beilstein J. Org. Chem. 2014, 10, 405–424, doi:10.3762/bjoc.10.38

• and extracts water, which is generated from the dissociated nitric acid. Usually, the sulfuric acid is used in excess in the preparation of the mixed acid. Therefore, in the presence of sulfuric acid nitrations are usually faster and selective. A variety of other acids including solid acids can be

Molecular rearrangements of superelectrophiles

• Douglas A. Klumpp

Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45

• become more widely appreciated and it is shown to involve both Brønsted and Lewis acids [8]. Moreover, superelectrophiles have been utilized in many synthetic conversions. While these reactions are often carried out in superacids, less acidic media (CF3CO2H, H2SO4, BF3·H2O, and solid acids) have also