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

• -free and greener synthesis of various N-substituted pyrroles 43 under solvent-free conditions (Scheme 20a). For the optimizations of the reaction conditions, various catalysts (Ca(NO3)2∙4H2O, UO2(NO3)2∙6H2O, Bi(NO3)2∙5H2O) and solvents (H2O, CH3CN, EtOH, DMSO, DMF, MeOH, CH2Cl2, no solvent) were

Improving the accuracy of ³¹P NMR chemical shift calculations by use of scaling methods

• William H. Hersh and
• Tsz-Yeung Chan

Beilstein J. Org. Chem. 2023, 19, 36–56, doi:10.3762/bjoc.19.4

An alternative C–P cross-coupling route for the synthesis of novel V-shaped aryldiphosphonic acids

• Stephen J. I. Shearan,
• Enrico Andreoli and
• Marco Taddei

Beilstein J. Org. Chem. 2022, 18, 1518–1523, doi:10.3762/bjoc.18.160

• Abstract The synthesis of phosphonate esters is a topic of interest for various fields, including the preparation of phosphonic acids to be employed as organic linkers for the construction of metal phosphonate materials. We report an alternative method that requires no solvent and involves a different

• aspects: we use no solvent and we employ a different order of addition of reactants. The absence of solvent presents a few advantages over the original method. First of all, the removal of said solvent by distillation after the completion of the reaction is no longer required and thus there is a

Electron-rich triarylphosphines as nucleophilic catalysts for oxa-Michael reactions

• Susanne M. Fischer,
• Simon Renner,
• A. Daniel Boese and
• Christian Slugovc

Beilstein J. Org. Chem. 2021, 17, 1689–1697, doi:10.3762/bjoc.17.117

• prepared with nucleophilic catalysis using 10 mol % N-heterocyclic carbenes such as 1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene or 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene. The polymerization was carried out at room temperature for 24 h and no solvent was used. The resulting reaction

• boxes) at room temperature (23 °C); no solvent used. Left: double-bond conversion of the polymerization of 4 initiated by 5 mol % TPP, MMTPP or TMTPP after 1 h at room temperature (23 °C) and at 80 °C as well as after 24 h at 23 °C and at 80 °C; light sections of the bars represent the share of Rauhut

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

• substituted hydrazones obviated their generation in situ, and as ethanol was identified as a better solvent in the initial coupling step, no solvent exchange was necessary in the fragmentation step of the hydrazide intermediate. The addition of triethylamine and heating the reaction to 80 °C for 1 hour were

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• monobutyltin oxide, using substoichiometric amounts of isosorbide and succinic acid and no solvent at 230 °C reaction temperature. Isosorbide is a safe chemical [246] that is obtainable on the large scale from renewable glucose [247][248]. Because of this and due to the inherent rigid structure, conferring the

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

• Thomas Schneider,
• Michael Keim,
• Bianca Seitz and
• Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

• compared with that of other dienophiles. Thus, other propyn-1-iminium salts with an internal C,C triple bond and not containing a CF3 substituent (toluene, 120 °C, several hours [28]), DMAD (no solvent, 170–180 °C, 1 h [36]) and hexafluoro-2-butyne (200 °C, 2 h [37]) react only under harsher conditions

Efficient synthesis of piperazinyl amides of 18β-glycyrrhetinic acid

• Dong Cai,
• ZhiHua Zhang,
• Yufan Meng,
• KaiLi Zhu,
• LiYi Chen,
• ChangXiang Yu,
• ChangWei Yu,
• ZiYi Fu,
• DianShen Yang and
• YiXia Gong

Beilstein J. Org. Chem. 2020, 16, 798–808, doi:10.3762/bjoc.16.73

• yield. The reaction was completed in 30 min. The principal advantages of this method are that there is no solvent required, and that the reaction time is shorter than in previous cases [16], since the acid formed during the reaction may catalyze the esterification reaction of 18β-glycyrrhetinic acid

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• critical assistant in the process, as the insolubility of the MX product can strongly shift the position of equilibrium and drive the reaction. Mechanochemical techniques can be used to provide a driving force for a reaction that would be energetically unfavorable and has no solvent assistance. The

Understanding the unexpected effect of frequency on the kinetics of a covalent reaction under ball-milling conditions

• Ana M. Belenguer,
• Adam A. L. Michalchuk,
• Giulio I. Lampronti and
• Jeremy K. M. Sanders

Beilstein J. Org. Chem. 2019, 15, 1226–1235, doi:10.3762/bjoc.15.120

• less expensive than traditional solution-based methods, because they require little or no solvent. Moreover, mechanochemical syntheses often give quantitative yields of products [2][3][4]. Manual or mechanical grinding can be performed “neat”, i.e., in the absence of solvent (neat grinding, NG

Extending mechanochemical porphyrin synthesis to bulkier aromatics: tetramesitylporphyrin

• Qiwen Su and
• Tamara D. Hamilton

Beilstein J. Org. Chem. 2019, 15, 1149–1153, doi:10.3762/bjoc.15.111

• substituents, the porphyrin product can be labor-intensive to produce and purify in good yield and large quantities using other methods. The process involves multiple condensations, together with oxidation that may happen in one pot or as separate steps. Other no-solvent-added methods of porphyrin synthesis

• could accommodate a sterically-hindered aldehyde, and produce TMP at room temperature and in the absence of added solvent for the condensation step, using relatively simple reaction conditions. The use of mechanochemistry to bring about a no-solvent-added acid-catalyzed condensation between aldehydes

• conditions, while the sealed-bomb reaction products are heavily contaminated with chlorins [27][28][29], byproducts that contain two more hydrogens than the porphyrin, and which easily undergo chemical oxidation to yield porphyrin. In contrast, since the no-solvent-added mechanochemical synthesis takes place

Halogen bonding and host–guest chemistry between N-alkylammonium resorcinarene halides, diiodoperfluorobutane and neutral guests

• Fangfang Pan,
• Mohadeseh Dashti,
• Michael R. Reynolds,
• Kari Rissanen,
• John F. Trant and
• Ngong Kodiah Beyeh

Beilstein J. Org. Chem. 2019, 15, 947–954, doi:10.3762/bjoc.15.91

• complexes, similar to that observed with our previous chloroform-involved 2:2 halogen-bonded complex [31]. In the present assembly, no solvent molecules are found in the encapsulated volume outlined by the two DIOFB molecules and so the two cavitands could be assigned. The absence of the guest molecules

• to fill the space. The relatively strong halogen bonds in 1&DIOFB_A partially account for its larger population occupancy than 1&DIOFB_B. In both modes, there is no solvent-accessible space between the dimerized resorcinarene salts. The halogen bond donors connect the two resorcinarene like a solid

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands

• Tegene T. Tole,
• Johan H. L. Jordaan and
• Hermanus C. M. Vosloo

Beilstein J. Org. Chem. 2019, 15, 194–209, doi:10.3762/bjoc.15.19

• an Agilent 7683B autosampler, HP-5 capillary column and an Agilent 5973 mass selective detector (MSD). The oven programme was used with either a two-minute solvent delay or no solvent delay. Helium was used as carrier gas with a 1.5 mL/min flow rate at 20 °C. The following general GC settings were

Synthesis of a tyrosinase inhibitor by consecutive ethenolysis and cross-metathesis of crude cashew nutshell liquid

• Jacqueline Pollini,
• Valentina Bragoni and
• Lukas J. Gooßen

Beilstein J. Org. Chem. 2018, 14, 2737–2744, doi:10.3762/bjoc.14.252

• , undergoes smooth ethenolysis only in dichloromethane as the solvent (Scheme 3). Using more sustainable solvents or no solvent at all, the reaction gave almost no turnover, regardless of the ruthenium catalyst employed. However, as a 1.1 M solution in dichloromethane, the unsaturated components of CNSL were

The enzymes of microbial nicotine metabolism

• Paul F. Fitzpatrick

Beilstein J. Org. Chem. 2018, 14, 2295–2307, doi:10.3762/bjoc.14.204

• methide, are still substrates, and there is no solvent isotope effect on amine oxidation. In addition, DHNO E350L/E352D has been developed as a reagent for stereospecific oxidation of a variety of (R)-amines, including a nicotine analog that does not contain an aromatic ring [24]. These results provide

Phosphodiester models for cleavage of nucleic acids

• Satu Mikkola,
• Tuomas Lönnberg and
• Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

• is almost completely deprotonated, lend further support for the mechanism in Scheme 3 [54][55][56]. No solvent D2O isotope effect occurs, consistent with rapid pre-equilibrium deprotonation of the attacking 2´-OH. For the departing 5´-O, the 18O KIE is normal, 16klg/18klg = 1.034 ± 0.004, and for the

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• ; nanoreactors; micelles; polymersomes; Introduction It is widely acknowledged that “the best solvent is no solvent”; however, running a reaction under neat conditions is very challenging from the points of view of mass transfer and temperature gradients [1][2]. Therefore, sustainable chemical technologies are

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• without any solvent (Table 1). In general, we noticed that more polar solvents (high dielectric constants) favour Z selectivity and a higher overall conversion, whereas the use of less polar or no solvent (lower dielectric constants) favour E selectivity and a lower overall conversion. As shown in Table 1

• ) or no solvent at all, the concentration of reactants is very high. This could cause the additional benzaldehyde to be close enough to the intermediate to react before the rotation occurs. To bolster further this argument, the highest amount of side product is observed in the absence of solvent, i.e

• preference for larger groups to be in equatorial positions in cyclohexane rings (Scheme 2). The E selectivity is driven by both the high concentrations of reactants and a low dielectric constant of the LAG solvent (or no solvent). To evaluate which might be playing a more critical role in the selectivity

Main group mechanochemistry

• Agota A. Gečiauskaitė and
• Felipe García

Beilstein J. Org. Chem. 2017, 13, 2068–2077, doi:10.3762/bjoc.13.204

• methodologies. Mechanochemistry [1][2][3][4][5][6][7][8][9][10] is an emerging solid state methodology involving the use of little or no solvent, with the potential to challenge the current dominance of ‘wet’ chemical synthesis [11][12][13][14][15]. From a purely synthetic point of view, it is clear that

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

Solvent-free, visible-light photocatalytic alcohol oxidations applying an organic photocatalyst

• Martin Obst and
• Burkhard König

Beilstein J. Org. Chem. 2016, 12, 2358–2363, doi:10.3762/bjoc.12.229

• solvent-free photocatalysis is the application of heterogeneous, semiconducting photocatalysts, often based on titanium dioxide and other metal oxides [6][7][8]. However, to the best of our knowledge, no solvent-free visible-light driven transformation of a solid substrate applying an organic

Donor–acceptor type co-crystals of arylthio-substituted tetrathiafulvalenes and fullerenes

• Xiaofeng Lu,
• Jibin Sun,
• Shangxi Zhang,
• Longfei Ma,
• Lei Liu,
• Hui Qi,
• Yongliang Shao and
• Xiangfeng Shao

Beilstein J. Org. Chem. 2015, 11, 1043–1051, doi:10.3762/bjoc.11.117

• divided into two types (I and II), except for 2·(C70)4·(PhCl)2. The ratio of donor:acceptor (abbreviated as D:A) for the type I and type II co-crystals are 1:1 and 1:2, respectively. No solvent molecule was involved in most of the type I co-crystals, except for 4·C60·CS2, which contains a small, linear

Properties of PTFE tape as a semipermeable membrane in fluorous reactions

• Brendon A. Parsons,
• Olivia Lin Smith,
• Myeong Chae and
• Veljko Dragojlovic

Beilstein J. Org. Chem. 2015, 11, 980–993, doi:10.3762/bjoc.11.110

• considerable solvent uptake. (b) The delivery tube is just touching the surface of the solution and there was almost no solvent uptake. Transport of dyed dimethyl phthalate in dichloromethane after (a) 0 h, (b) 1 h, (c) 2 h, (d) 3 h and dyed dimethyl phthalate in hexanes after (e) 0 h, (f) 1 h, (g) 2 h, (h) 3

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• an effective KA2-MCR, that is, the substitution of aldehyde partners with less reactive ketones. This issue was partially solved by Ji and co-workers, who found with AuBr3 (4 mol %), no-solvent and 60 °C the best conditions to react alkyl ketones, secondary amines and aryl/alkylacetylenes to give the

Acid, silver, and solvent-free gold-catalyzed hydrophenoxylation of internal alkynes

• Marcia E. Richard,
• Daniel V. Fraccica,
• Kevin J. Garcia,
• Erica J. Miller,
• Rosa M. Ciccarelli,
• Erin C. Holahan,
• Victoria L. Resh,
• Aakash Shah,
• Peter M. Findeis and
• Robert A. Stockland Jr.

Beilstein J. Org. Chem. 2013, 9, 2002–2008, doi:10.3762/bjoc.9.235

• . aChlorogold precursor (0.32–0.37 mmol), 2 equiv arylboronic acid, 2 equiv Cs2CO3, 50 °C, 20 min, iPrOH (1.5 mL), microwave irradiation. bIsolated yields. cTHF was used as the solvent. Hydrophenoxylation of alkynesa,b. aAlkyne (0.28 mmol), phenol (0.56 mmol), 130 °C, 20 min, no solvent. bIsolated yields

• . cMicrowave heating with 1 as the catalyst (14.0 μmol, 5%). dConventional heating with 7 as the catalyst (14.0 μmol, 5%). Microwave assisted synthesis of arylgold compounds. Regioselectivity of the addition reaction using arylgold precatalysts. Alkyne (0.28 mmol), phenol (0.56 mmol), 130 °C, 20 min, no

• solvent. Microwave heating with 1 or 7 as the catalyst (14.0 μmol, 5%). The yield of the addition product and ratio of regioisomers was determined by 1H NMR spectroscopy using anisole as an internal standard. Hydrophenoxylation of unactivated internal alkynes.a Supporting Information Supporting