A versatile route towards 6-arylpipecolic acids

• Erich Gebel,
• Cornelia Göcke,
• Carolin Gruner and
• Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 1104–1115, doi:10.3762/bjoc.21.88

• product 4 (Scheme 5a). The transformation of the enamine had to be carried out by reduction of the N-acyliminium ion by NaBH3CN in the presence of TFA, as Pd/C with H2 would lead also to the reduction of the triple bond. The products (2R,6S)-13 and (2R,6R)-13 were obtained in a 1:1 ratio (Scheme 5b

• given by switching one in an equatorial position. Using Pd/C and H2 for hydrogenation reactions usually leads to reduction of double or triple bonds, while aromatic systems tend not to be affected [58]. However, 3m and 3p undergo hydrogenation in the aromatic moiety, while 3p displays a complete

• )-9 are generated in a 1:1 ratio, while a hydrogenation of the N-formyl enamine with Pd/C and H2 favours the (2R,6S)-9 diastereomer. Moreover, an in-depth NMR analysis, focusing on coupling constants and subsequent dihedral angles of diastereomers (2R,6S)-9 and (2R,6R)-9, as well as selected

Recent total synthesis of natural products leveraging a strategy of enamide cyclization

• Chun-Yu Mi,
• Jia-Yuan Zhai and
• Xiao-Ming Zhang

Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81

• aldol condensation of 5 provided the tetracyclic α,β-unsaturated enone 6 in 57% yield. Subsequent catalytic hydrogenation using Pd/C conditions delivered the hydrogen to the alkene from the less hindered face, producing ketone 7 with high diastereoselectivity. Final reduction of both the amide and

Studies on the syntheses of β-carboline alkaloids brevicarine and brevicolline

• Benedek Batizi,
• Patrik Pollák,
• András Dancsó,
• Péter Keglevich,
• Gyula Simig,
• Balázs Volk and
• Mátyás Milen

Beilstein J. Org. Chem. 2025, 21, 955–963, doi:10.3762/bjoc.21.79

• : the formation of compound 31 was always observed, and brevicolline ((±)-1) was not formed. Interestingly, our attempts made for the transformation of compound 31 by dehydrogenative aromatization to brevicolline ((±)-1) by using several reagents (DDQ, Pd/C, MnO2, CuCl2, I2, elemental sulfur, KMnO4

Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines

• Muhammad Hasan,
• Anatoly A. Peshkov,
• Syed Anis Ali Shah,
• Andrey Belyaev,
• Chang-Keun Lim,
• Shunyi Wang and
• Vsevolod A. Peshkov

Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74

• scaffolds (Scheme 6) [64][65]. First, we attempted heterogeneous hydrogenation of the alkene functionality in compound 16a under 1 atm hydrogen pressure using Pd/C as a catalyst. Although the reaction proved sluggish, we were able to drive it to completion over a prolonged reaction time of 14 days

Dicarboxylate recognition based on ultracycle hosts through cooperative hydrogen bonding and anion–π interactions

• Wen-Hui Mi,
• Teng-Yu Huang,
• Xu-Dong Wang,
• Yu-Fei Ao,
• Qi-Qiang Wang and
• De-Xian Wang

Beilstein J. Org. Chem. 2025, 21, 884–889, doi:10.3762/bjoc.21.72

• reorganization likely involves the cleavage and re-formation of the dynamic Ctriazine–OAr bonds, and the presence of an excess of base could facilitate the formation of the thermodynamic-favored reorganized products [29][31]. The benzyl groups were subsequently removed under Pd/C and H2 conditions to afford the

Regioselective formal hydrocyanation of allenes: synthesis of β,γ-unsaturated nitriles with α-all-carbon quaternary centers

• Seeun Lim,
• Teresa Kim and
• Yunmi Lee

Beilstein J. Org. Chem. 2025, 21, 800–806, doi:10.3762/bjoc.21.63

• % yield under basic conditions using sodium hydroxide and tert-butanol. The reduction of nitrile 3q with lithium aluminum hydride generated amine 7 in an 85% yield, whereas the selective hydrogenation of the alkene moiety of 3q using a Pd/C catalyst in a H2 gas environment smoothly produced product 8 in a

Cryptophycin unit B analogues

• Thomas Schachtsiek,
• Jona Voss,
• Maren Hamsen,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2025, 21, 526–532, doi:10.3762/bjoc.21.40

• formation and N-Boc-protection [24] provided nitroarene 5 in 40% yield over three steps. Reduction of the nitro group was performed with Pd/C and hydrogen to obtain aniline 6 in 98% yield, which served as a precursor for mono- and dimethylated unit B derivatives 7 and 8, respectively. While dimethylaniline

• control of equivalents and pH, or Leuckart–Wallach-like reaction with ammonium formate and Pd/C [25] provided monomethylaniline 7 in 37% and 35% yield, respectively. The absolute structure of monomethylaniline 7 was confirmed by single-crystal X-ray diffraction measurements (Figure 2). Compound 7

• % probability. Synthesis of modified unit B derivatives. a) HNO3, H2SO4, 0 °C, 5 h, 48% (isolated as monohydrate); b) SOCl2, MeOH, 0 °C, 90 min, then reflux, 17 h, 95%; c) Boc2O, NEt3, MeCN, H2O, rt, 22 h, 88%; d) H2, Pd/C, MeOH, rt, 25 h, 98%; e) either: formalin, NaBH3CN, HOAc, MeOH, rt, 20 min, 37%, or

The effect of neighbouring group participation and possible long range remote group participation in O-glycosylation

• Rituparna Das and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2025, 21, 369–406, doi:10.3762/bjoc.21.27

• the presence of Pd-C. This deprotection protocol also facilitates an orthogonal deprotection strategy in multistep oligosaccharide syntheses in the presence of benzyl (OBn) groups (Scheme 6). The benzyl and cyanopivaloyl-protected hexarhamnoside derivative 37 was completely deprotected by a single

Synthesis of fluorinated acid-functionalized, electron-rich nickel porphyrins

• Mike Brockmann,
• Jonas Lobbel,
• Lara Unterriker and
• Rainer Herges

Beilstein J. Org. Chem. 2024, 20, 2954–2958, doi:10.3762/bjoc.20.248

• ether synthesis with 2-hydroxy-3,4,5-trimethoxybenzaldehyde (21). Conditions: a) K2CO3, benzyl bromide, abs. MeCN, N2, reflux, 18 h; b) TEMPO, KBr, NaOCl, NaHCO3, MeCN, rt, 76 h; c) MeOH, H2SO4, reflux, 18 h; d) Pd/C, H2, EtOH, rt, 24 h; e) Tf2O, pyridine, DCM, rt, 18 h. Synthesis of perfluoroalkyl

N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

The scent gland composition of the Mangshan pit viper, Protobothrops mangshanensis

• Jonas Holste,
• Paul Weldon,
• Donald Boyer and
• Stefan Schulz

Beilstein J. Org. Chem. 2024, 20, 2644–2654, doi:10.3762/bjoc.20.222

• concentrated under a stream of N2. Hydrogenation: The solvent of the natural extract (100 µL) was removed with a stream of N2 and taken up in pentane (100 µL) and a catalytic amount of Pd/C was added. The reaction was then stirred for 1 h under a H2 atmosphere. The catalyst was filtered and rinsed with pentane

The Groebke–Blackburn–Bienaymé reaction in its maturity: innovation and improvements since its 21st birthday (2019–2023)

• Cristina Martini,
• Muhammad Idham Darussalam Mardjan and
• Andrea Basso

Beilstein J. Org. Chem. 2024, 20, 1839–1879, doi:10.3762/bjoc.20.162

Syntheses and medicinal chemistry of spiro heterocyclic steroids

• Laura L. Romero-Hernández,
• Ana Isabel Ahuja-Casarín,
• Penélope Merino-Montiel,
• Sara Montiel-Smith,
• José Luis Vega-Báez and
• Jesús Sandoval-Ramírez

Beilstein J. Org. Chem. 2024, 20, 1713–1745, doi:10.3762/bjoc.20.152

• of 10% Pd/C and 5% Pd/CaCO3 yielded reduced compound 19. Cleavage of the THP group with Amberlist-15® resin and a final Jones oxidation of the primary alcohol to the carboxylic acid, led to cyclization with the 17β-OH group affording the lactone 20 in a moderate overall yield (Scheme 6). Biological

Methyltransferases from RiPP pathways: shaping the landscape of natural product chemistry

• Maria-Paula Schröder,
• Isabel P.-M. Pfeiffer and
• Silja Mordhorst

Beilstein J. Org. Chem. 2024, 20, 1652–1670, doi:10.3762/bjoc.20.147

• cyanoborohydride as a mild reducing agent, and paraformaldehyde as a methylating agent [36]. Methanol can be used as the methylating reagent in other methods. Here, a palladium on carbon (Pd/C) catalyst processes the dehydrogenation of the alcohol to form the corresponding aldehyde. The subsequently formed imine

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM)

• Fátima C. Teixeira,
• António P. S. Teixeira and
• C. M. Rangel

Beilstein J. Org. Chem. 2024, 20, 1623–1634, doi:10.3762/bjoc.20.145

• desired product. Compound 6 [51] was subsequently reduced to the corresponding aniline derivative 4 [52] in the presence of H2 and Pd/C (Scheme 1). The synthesis of diethyl (4-hydroxyphenyl)methylphosphonate (7) [53] started from [4-(benzyloxy)phenyl]methanol (8). Compound 8 was submitted to a

• ]methylphosphonate (10). The following hydrogenolysis under H2/Pd/C conditions in ethanol, afforded the desired diethyl (4-hydroxyphenyl)methylphosphonate (7), in an overall yield of 80%. The synthesis of diethyl [hydroxy(4-hydroxyphenyl)methyl]phosphonate (11) [55] started with the reaction of 4-hydroxybenzaldehyde

• ). Compound 15 reacted with diethyl phosphonate in the presence of a strong base (sodium methoxide) to afford diethyl [hydroxy(4-nitrophenyl)methyl]phosphonate (16) in 81% yield (Scheme 4). The hydrogenolysis of this compound under H2 on Pd/C afforded quantitatively diethyl [hydroxy(4-aminophenyl)methyl

Electrocatalytic hydrogenation of cyanoarenes, nitroarenes, quinolines, and pyridines under mild conditions with a proton-exchange membrane reactor

• Koichi Mitsudo,
• Atsushi Osaki,
• Haruka Inoue,
• Eisuke Sato,
• Naoki Shida,
• Mahito Atobe and
• Seiji Suga

Beilstein J. Org. Chem. 2024, 20, 1560–1571, doi:10.3762/bjoc.20.139

• semihydrogenation of alkynes to form Z-alkenes using a PEM reactor [31]. The Pd/C catalyst was essential for the reaction. They recently found that a PEM reactor with a Rh/C catalyst was effective for the stereoselective reduction of cyclic ketones [40]. Nagaki et al. reported the electrochemical deuteration of

• a PEM reactor (Table 1). Humidified hydrogen was used as a proton source, and 4.0 F mol−1 of electricity was passed to a circulated solution of 1a (for the details, see the Supporting Information File 1). When Pd/C was used as the cathode catalyst, benzylamine (2a) was not obtained (Table 1, entry 1

• ), the charge for screening was set to 2.0 F mol−1 for rapid evaluation, and several cathode catalysts were examined. When Pd/C was used as the cathode, the reaction did not proceed (Table 3, entry 1). The desired reduction proceeded with Ru/C and 5a was obtained in 79% of current efficiency (Table 3

Synthesis of 1,4-azaphosphinine nucleosides and evaluation as inhibitors of human cytidine deaminase and APOBEC3A

• Maksim V. Kvach,
• Stefan Harjes,
• Harikrishnan M. Kurup,
• Geoffrey B. Jameson,
• Elena Harjes and
• Vyacheslav V. Filichev

Beilstein J. Org. Chem. 2024, 20, 1088–1098, doi:10.3762/bjoc.20.96

• racemisation, and nucleoside 14 with the same α/β ratio of 3:2 formed from either anomerically pure 17 or from a mixture of the anomers. Catalytic hydrogenation is usually used for the removal of benzyl protecting groups. However, standard hydrogenation conditions using 10% Pd/C led to reduction of the C=C

• ) H2, Pd/C, CH2Cl2, rt, 3 h; b) chloroacetyl chloride, Et3N, 0 °C, overnight, 38% yield; iii) 10, HMDS, DCE, 90 °C, 24 h, 32% yield; iv) TMSOTf, ACN, 40 °C, 2.5 h, 64% yield. i) H2, 5% Pd/CaCO3/3% Pb, Et3N, CH2Cl2, rt, 1.5 h, 34% and 21% yield for α- and β-anomer of 18, respectively; ii) H2, 10% Pd/C

Structure–property relationships in dicyanopyrazinoquinoxalines and their hydrogen-bonding-capable dihydropyrazinoquinoxalinedione derivatives

• Tural N. Akhmedov,
• Ajeet Kumar,
• Daken J. Starkenburg,
• Kyle J. Chesney,
• Khalil A. Abboud,
• Novruz G. Akhmedov,
• Jiangeng Xue and
• Ronald K. Castellano

Beilstein J. Org. Chem. 2024, 20, 1037–1052, doi:10.3762/bjoc.20.92

• secured due to the favorable hydrogen bonding (O–H∙∙∙N) between the oxime units; this idea is supported by 1H NMR spectroscopy which shows the presence of two distinct hydroxyl proton signals. The reduction of 7d in the presence of Pd/C and hydrazine monohydrate afforded 1,10-phenanthroline-5,6-diamine

Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• % yield. Compound 4a could be hydrogenated to the corresponding reduction product 12 using Pd/C and ammonium formate conditions (Scheme 6a). Notably, as shown in Scheme 6b, treatment of the unsaturated γ-AA derivative 6a with Pd/C and ammonium formate led to a cyclization reaction, furnishing γ-lactam 13

• amines. Scale-up reactions and synthetic transformations. Reaction conditions: a) LiAlH4, THF, 0 °C; b) MeMgBr, THF, rt to reflux; c) NaOH, MeOH, 60 °C, d) EDCI, DMAP, BnNH2, DCM, rt; e) EDCI, DMAP, Et3N, HN(OMe)(Me)·HCl, DCM, rt; f) MeMgBr, THF, 0 °C to rt; g) Pd/C, HCO2NH4, 65 °C. For more details, see

Optimizations of lipid II synthesis: an essential glycolipid precursor in bacterial cell wall synthesis and a validated antibiotic target

• Milandip Karak,
• Cian R. Cloonan,
• Brad R. Baker,
• Rachel V. K. Cochrane and
• Stephen A. Cochrane

Beilstein J. Org. Chem. 2024, 20, 220–227, doi:10.3762/bjoc.20.22

• , followed by in situ re-acetylation of the C2-amino group and C6-alcohol with acetic anhydride, resulting in the formation of disaccharide 4 in a one-pot fashion. The anomeric benzyl protecting group in disaccharide 4 was then removed via a Pd/C-catalyzed hydrogenation reaction, producing a mixture of α/β

Photoinduced in situ generation of DNA-targeting ligands: DNA-binding and DNA-photodamaging properties of benzo[c]quinolizinium ions

• Julika Schlosser,
• Olga Fedorova,
• Yuri Fedorov and
• Heiko Ihmels

Beilstein J. Org. Chem. 2024, 20, 101–117, doi:10.3762/bjoc.20.11

• of 3,4-dimethoxybenzaldehyde with 5-substituted 2-picoline derivatives in low to moderate yields ranging from 13% (2f) to 65% (2a) (Scheme 2). The amino-substituted derivative 2b was synthesized by reduction of the nitrostyrylpyridine 2a with Pd/C and hydrazine in 83% yield. Subsequent acylation of

• : piperidine, MeOH, reflux (2a,c), ii: Ca(OTf)2, Bu4NPF6, 130 °C (2d,f), iii: N2H4·H2O, Pd/C, MeOH, reflux (2b), iv: NaNO2, CuCl, aq HCl (37%), room temp., 2 h, 60 °C, 30 min (2e), v: acetyl chloride, pyridine, THF, room temp. (2g). Photoinduced formation of styrylpyridine derivatives 2b–g to the benzo[c

Synthetic approach to 2-alkyl-4-quinolones and 2-alkyl-4-quinolone-3-carboxamides based on common β-keto amide precursors

• Yordanka Mollova-Sapundzhieva,
• Plamen Angelov,
• Danail Georgiev and
• Pavel Yanev

Beilstein J. Org. Chem. 2023, 19, 1804–1810, doi:10.3762/bjoc.19.132

• , Pd/C, CH3OH, rt. See main text for details. Yields of α-(o-nitrobenzoyl)-β-enamino amides 3 prepared according to Scheme 1. Yields of β-enaminoketones 6 prepared by decarbamoylation of intermediates 3, according to Scheme 2: Yields of 2-alkyl-4-quinolone-3-carboxamides 5, prepared according to Scheme

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

• /toluene 1:10 mixture under inert atmosphere to afford 2-amino-3-nitro-meso-tetraarylporphyrins which on reduction through sodium borohydride in the presence of 10% Pd/C in CH2Cl2/MeOH provided the desired porphyrins 1 in good yields as key starting materials for the synthesis of newly designed benzo[f

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• transition metal (Ni, Fe, V) porphyrin catalysts and oxygen. Catalytic reduction (H2, Pd/C) affords 2,2'-diaminobibenzyl (20) in the subsequent step [28]. 1.2 Ring-closing via amine condensation The initial synthesis of 10,11-dihydro-5H-dibenzo[b,f]azepine (2a) was reported in 1899 by Thiele and Holzinger

• 1a in poor yield (20–50%) [39]. The starting material 2a was distilled through a heated (≈150 °C) column packed with Pd/C and glass wool. Crude 1a was collected as a solid and purified. Further research has been conducted on the effect of catalyst choice and composition for large scale synthesis

Synthesis of medium and large phostams, phostones, and phostines

• Jiaxi Xu

Beilstein J. Org. Chem. 2023, 19, 687–699, doi:10.3762/bjoc.19.50

• followed by hydrogenolysis in the presence of Pd/C as a hapten to produce an antibody. The antibody can catalyze the formation of a difficultly synthesized 14-membered lactone [24]. 2 Synthesis via annulations Annulations are alternative strategies for the synthesis of medium and large phostam, phostone