Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• chemistry; Introduction The terminology “molecular tweezers” was first introduced by Chen and Whitlock in 1978 through a seminal paper [1], wherein they presented a water-soluble molecular receptor composed of two caffeine recognition units linked by a semi-rigid diyne spacer. This ingenious design enabled

Synthesis of α-(perfluoroalkylsulfonyl)propiophenones: a new set of reagents for the light-mediated perfluoroalkylation of aromatics

• Durbis J. Castillo-Pazos,
• Juan D. Lasso and
• Chao-Jun Li

Beilstein J. Org. Chem. 2022, 18, 788–795, doi:10.3762/bjoc.18.79

• products impossible. Furthermore, we tested this methodology on caffeine (Scheme 5), leading to a lower yield of products 15b and c, due to its less electron-rich nature [26]. However, this yield was concordant with other radical innate functionalizations reported in the literature, showing the potential

• perfluoroalkylation of electron-rich aromatics, as well as in the late-stage functionalization of small molecules such as caffeine, which is of great interest in the current literature [28]. In future work, we will explore the reach and applicability of these reagents for the functionalization of compounds of

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• formation of a new derivative of caffeine. Keywords: adenine; caffeine; cyclic dimer of hexafluorothioacetone; hexafluoroisopropyl group; purine; 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane; theophylline; Introduction Despite significant progress in the last 20–30 years, the selective introduction of

• = 7.69 ppm, 2H, br. s) was observed for the NH2 group. We believe that these observations are consistent with the restricted rotation of the CH(CF3)2 group because of the proximity to the amino group. Theobromine or caffeine both were found to be inert towards tetrakis(trifluoromethyl)-1,3-dithietane (1

• caffeine analogue, modified by the attachment of two CF3 groups to the methyl group. This is the first example of an introduction of a fluoroalkyl group bigger than CF3 or CF2H into a theophylline (7) molecule, since known examples of fluorinated caffeine derivatives are limited to 7-trifluoromethyl

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• , high stability, and high selectivity (Scheme 25). Recently, Heydari et al. reported a Cu(I)–caffeine complex supported on silica-coated magnetite nanoparticles, Fe3O4@SiO2–caffeine–Cu(I) (121), for “click” reactions in aqueous medium [96]. The heterogeneous catalyst 121 was prepared as outlined in

• heated at reflux for 18 h to obtain new nanoparticles. The resulting nanoparticles were magnetically collected and washed with toluene, methanol, and diethyl ether. These new nanoparticles were treated with caffeine (119) in dry acetone under reflux conditions for 48 h. The resulting nanoparticles 120

• were magnetically collected and washed with methanol and acetone. Finally, the nanoparticles Fe3O4@SiO2–caffeine–Cu(I) (121) were prepared by the reaction of the nanoparticles Fe3O4@SiO2–caffeine (120), CuI, and KOt-Bu in dry THF at rt for 12 h. The final nanoparticles 121 were magnetically collected

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

• products from the catalyst. The catalyst showed good catalytic activity for four successive runs [47]. Tayebee and co-workers prepared 3-sulfo-imidazolopyridinium hydrogen sulfate ([Simp]HSO4, 53) as a new natural ionic liquid by the reaction between caffeine (51) as a natural, inexpensive, and available

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• caffeine. The yields are good (44–92%), with regioselectivity being observed in a few cases. As with the trifluoromethylation by Pitre et al., this procedure does fit all the criteria for LSF, as it is very mild and simple, even though no complex structures are exemplified. Although it does not fit the

Exploring mechanochemistry to turn organic bio-relevant molecules into metal-organic frameworks: a short review

• Vânia André,
• Sílvia Quaresma,
• João Luís Ferreira da Silva and
• M. Teresa Duarte

Beilstein J. Org. Chem. 2017, 13, 2416–2427, doi:10.3762/bjoc.13.239

• enhancement of MOF structural and stability properties [90][91]. Bioactive molecules like caffeine [92][93] and anticancer drugs [94][95][96][97][98] were incorporated in ZIF-8 and tests proved that these systems allowed for a controlled drug release. Further studies involving ZIF-8 with encapsulated

• of caffeine into ZIF-8 [98] and Zhuang et al. proposed a method to synthesize nanosized ZIF-8 spheres with encapsulation of small molecules into the framework during synthesis [95]. Also, Zheng et al. proposed a fast, single step synthesis of ZIF-8 with direct incorporation of small molecules

Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins

• Alexei N. Kiselev,
• Olga K. Grigorova,
• Alexei D. Averin,
• Sergei A. Syrbu,
• Oskar I. Koifman and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2017, 13, 1524–1532, doi:10.3762/bjoc.13.152

• corresponding coupling products with benzoxazole and benzothiazole (Table 2, entries 9 and 10), and with N-methylbenzimidazole the yield of 8 reached 90% (Table 2, entry 11). However, the best result was obtained with caffeine (95%, Table 2, entry 12) which turned to be the most active reagent in the series

• benzothiazole, benzoxazole, N-methylbenzimidazole and caffeine. Plausible action of palladium and copper catalysts with transmetalation step. Dirylation of zinc di-meso-(bromophenyl)porphyrinates 10–12 with benzothiazole, benzoxazole and N-methyl benzimidazole. Polyarylation of zinc tetrakis-meso-(bromophenyl

• )porphyrinate 18 with benzoxazole. Arylation of zinc meso-(bromophenyl)porphyrinates 1, 2 with benzothiazole and benzoxazole (reaction time 24 h). Arylation of zinc meso-(bromophenyl)porphyrinates 1, 2 with benzothiazole, benzoxazole, N-methylbenzimidazole and caffeine (conditions: Pd(OAc)2/Cu(OAc)2 (20:20 mol

Extrusion – back to the future: Using an established technique to reform automated chemical synthesis

• Deborah E. Crawford

Beilstein J. Org. Chem. 2017, 13, 65–75, doi:10.3762/bjoc.13.9

• scaled up to several hundred grams and carried out continuously by employing hot melt extrusion (HME) [31][34]. Initially two cocrystals were optimised – a cocrystal formed from caffeine and oxalic acid and another consisting of AMG517 (a selective TRPV1 antagonist) and sorbic acid [31]. Since the

• stoichiometry could potentially lead to undesirable variations in the properties of the product. Kulkarni et al., however, demonstrated that this issue could be resolved by careful manipulation of the extruder temperature [36], demonstrating that in the extrusion of a 2:1 mixture of caffeine/malic acid

A journey in bioinspired supramolecular chemistry: from molecular tweezers to small molecules that target myotonic dystrophy

• Steven C. Zimmerman

Beilstein J. Org. Chem. 2016, 12, 125–138, doi:10.3762/bjoc.12.14

• report [8] of compound 2 containing two caffeine units linked by a rigid diyne spacer (Figure 2e). Whitlock noted that conventional bisintercalators such as 1 would have their affinity for oligonucleotides significantly reduced as a result of intramolecular π–π aromatic stacking. Whereas the diyne spacer

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• the presence of sulfate anions [30]. The photoaddition reaction involved in the degradation of RF has been found to be further enhanced in the presence of caffeine which results in a further decrease of the fluorescence of RF in phosphate buffer [35]. The phosphate anions have also been found to

• of RF photostabilization. Caffeine (CF) is known to form molecular complexes with RF [10][40][106][107][108][109][110] and thus slow down its rate of chemical [76] and photodegradation reactions [29][68]. A pH around 6 has been reported to be most suitable for the stabilization of RF in the presence

Novel supramolecular affinity materials based on (−)-isosteviol as molecular templates

• Christina Lohoelter,
• Malte Brutschy,
• Daniel Lubczyk and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2013, 9, 2821–2833, doi:10.3762/bjoc.9.317

• significant application as receptors and chemical sensors in the detection of aromatic compounds [16][17][18][19][20]. Thus, the first artificial receptor for caffeine had been established [21][22]. The introduction of chiral information onto a supramolecular entity gave rise for enantiofacial differentiation