Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• , dioxane/water; d) NaIO4, then NaOCl2, H2NSO3H; e) MeI, K2CO3, acetone; f) AcOH, H2O; g) NaOH, MeOH; h) PDC, DMF; i) CF3COOH, CH2Cl2; j) H2, 5% Pd/C, MeOH, H2O. Two-carbon homologation of the protected L-serine. Reagents and conditions: a) Fmoc-succinimide, Na2CO3, dioxane, H2O; b) (3-hydroxymethyl)-3

• O-benzyl-L-serine. Reagents and conditions: a) (CF3CH2O)2P(O)CH2COOMe, KHMDS, 18-crown-6; b) I2, MeCN; c) Bu3SnH, AIBN, benzene, reflux; d) H2, 10% Pd/C, ethanol; e) CrO3, acetone, then CH2N2, ether; f) 3 M HCl, 80 °C. Synthesis of (2S,3R)-2 employing a one-pot cis-olefination–conjugate addition

• . Reagents and conditions: a) NaClO2, 30% H2O2, NaH2PO4, MeCN; b) ClCOOEt, NEt3, then CH2N2, ether; c) MeOH, PhCOOAg, NEt3; d) LiOH, THF/H2O; e) ClCOOBn, NEt3, DMAP; f) TFA, H2O; g) NaIO4, acetone/water; h) NaHCO3, THF/H2O; i) H2C=CHCH2Br, NaHCO3, DMF; j) H2, 10% Pd/C, MeOH/HCl. Synthesis of (4S)-4-hydroxy-L

Novel solid-phase strategy for the synthesis of ligand-targeted fluorescent-labelled chelating peptide conjugates as a theranostic tool for cancer

• Sagnik Sengupta,
• Mena Asha Krishnan,
• Premansh Dudhe,
• Ramesh B. Reddy,
• Bishnubasu Giri,
• Sudeshna Chattopadhyay and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2018, 14, 2665–2679, doi:10.3762/bjoc.14.244

• (tert-butoxy) protected DUPA precursor 3 (0.250 g, 0.434 mmol) in dichloromethane (10 mL), 10 mol % Pd/C (40 mg) was added. The reaction mixture was hydrogenated under an atmosphere of H2 gas (1 atm) for 24 h at room temperature. After completion of the reaction, Pd/C was filtered off through a celite

• tris(tert-butoxy) protected DUPA ligand 4. Reagents and conditions: (a) Triphosgene, triethylamine, dichloromethane (DCM), −50 °C to rt; (b) L-glutamic acid γ-benzyl-α-tert-butylester hydrochloride, triethylamine, DCM, rt, overnight; (c) H2, Pd/C, CH2Cl2, 24 h, rt. Attempted synthesis of PSMA targeted

Synthesis of a leopolic acid-inspired tetramic acid with antimicrobial activity against multidrug-resistant bacteria

• Luce Mattio,
• Loana Musso,
• Leonardo Scaglioni,
• Andrea Pinto,
• Piera Anna Martino and
• Sabrina Dallavalle

Beilstein J. Org. Chem. 2018, 14, 2482–2487, doi:10.3762/bjoc.14.224

• ) triphosgene, DIEA, DCM, rt, 3 h, 50%; d) trifluoroacetic acid, DCM, rt, 3 h, 95%; e) pentafluorophenol, DCC, EtOAc, 0 °C, 1h, then rt, 3 h, 60%. Synthesis of compound 1. Reagents and conditions: a) n-BuLi, THF, −60 °C, 220 min, 60%; b) H2, Pd/C 10%, AcOEt, rt, 100 min, 72%. Supporting Information Supporting

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• %). Next, exposure of the diallyl derivative 73a to G-II catalyst 2 yielded the cyclized product 74 (72%). Eventually, hydrogenation of the RCM product 74 was achieved with H2, Pd/C conditions to give the saturated 2,3,4,5-tetrahydro-1-benzazepine 75 in 81% yield (Scheme 11). Naphthoxepine derivatives play

• %). Subsequently, hydrogenation of compounds 126 and 125 was accomplished with H2 under Pd/C catalysis conditions to afford the respective saturated macrocyclic products 127 (80%) and 128 (90%). Since the small ring cyclophane is highly strained, compound 125 was formed as a minor product (Scheme 19). Recently, Li

A novel and practical asymmetric synthesis of eptazocine hydrobromide

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan,
• Kuaile Lin and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 2340–2347, doi:10.3762/bjoc.14.209

• replaced with HOAc/H2O (2:1) or Pd/C was selected as a catalyst, the reaction gave a similar result as with Raney-Ni as catalyst in NH3/CH3OH. It seems that compound 5 easily reacted with the carbonyl group to form the five-membered ring. Since the carbonyl group is necessary for the following Mannich

• improved the reaction yield (Table 3, entries 4 and 5). The reductive methylation of 14 under Eschweiler–Clarke conditions (HCOOH/formalin/reflux) furnished 15 in quantitative yield. The latter was reduced by NaBH4 in methanol at room temperature, and then dehydration and hydrogenation with H2/Pd/C in

Semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues

• Kai Zhang,
• Jiarong Li,
• Honglin Liu,
• Haiyou Wang and
• Lamusi A

Beilstein J. Org. Chem. 2018, 14, 2321–2330, doi:10.3762/bjoc.14.207

• , and then 10% Pd/C (0.36 g, 0.33 mmol) was added. The mixture was stirred under hydrogen at room temperature for 48 h. The mixture was then filtered. The filtrate was evaporated under reduced pressure, and the residue was purified by column chromatography on silica gel (200–300 mesh) to afford pure 1

Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH

• Femke Beiroth,
• Tomas Koudelka,
• Thorsten Overath,
• Stefan D. Knight,
• Andreas Tholey and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163

• efficiency. Synthesis of photolabile α-D-mannosides 3 and 4. a) H2, Pd-C, methanol, rt, 6 h, 94%; b) HATU, DIPEA, dry DMF, N2, rt, overnight, quant.; c) 1. 50% TFA in water, rt, 3 h; 2. HATU, 8, DIPEA, dry DMF, N2, rt, 14 h, 19% (over 2 steps); d) dry methanol, rt, 16 h, 59%; e) Et3N, dry methanol, rt, 15 h

Water-soluble SNS cationic palladium(II) complexes and their Suzuki–Miyaura cross-coupling reactions in aqueous medium

• Alphonse Fiebor,
• Richard Tia,
• Banothile C. E. Makhubela and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1859–1870, doi:10.3762/bjoc.14.160

• relatively low energy barrier indicates that the reaction proceeds at a fast rate in getting to the intermediate (IM1), thus it is kinetically favoured. The reaction then proceeds via transition state TS2, leading to the cleavage of the C(sp2)–Br bond and the formation of a new Pd–C(sp2) bond, to form a cis

• intermediate of energy −93.0 kcal/mol. The new Pd–C(sp2) bond distance of 2.00 Å falls within the reported Pd–C(sp2) bond distances [47][48]. Since the bromo ligand is larger in atomic radius than the chloro ligands the more stable form of the oxidative addition product is the trans form. As such, the cis

• product can isomerise to a more stable trans intermediate of energy −93.6 kcal/mol having a Pd–C(sp2) bond length of 1.99 Å. Next, under the optimal conditions with 17d as a catalyst (since it provided the highest yield in the presence of TBAB, Table 2, entry 26), we examined the substrate scope with

Cobalt–metalloid alloys for electrochemical oxidation of 5-hydroxymethylfurfural as an alternative anode reaction in lieu of oxygen evolution during water splitting

• Jonas Weidner,
• Stefan Barwe,
• Kirill Sliozberg,
• Stefan Piontek,
• Justus Masa,
• Ulf-Peter Apfel and
• Wolfgang Schuhmann

Beilstein J. Org. Chem. 2018, 14, 1436–1445, doi:10.3762/bjoc.14.121

• oxidation of HMF on carbon black supported monometallic Pd/C and Au/C, and bimetallic Pd-Au/C catalysts [27]. Their studies revealed that the reaction pathway was influenced by the type of catalyst and the applied potential [27]. Furthermore, Choi and Cha found that the overpotential required to initiate

Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles

• Dennis Hiltrop,
• Steffen Cychy,
• Karina Elumeeva,
• Wolfgang Schuhmann and
• Martin Muhler

Beilstein J. Org. Chem. 2018, 14, 1428–1435, doi:10.3762/bjoc.14.120

• structural similarity of the possible oxidation products makes the assignment of occurring IR bands to certain species challenging. Glycerol oxidation was studied over different catalytically active metals, such as Au [15], AuAg/C [16], Pt [17][18], Au/C [19][20], Pt/C [20][21], Pd/C [20], PdAu/C [22], PdNi

Enantioselective phase-transfer catalyzed alkylation of 1-methyl-7-methoxy-2-tetralone: an effective route to dezocine

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 1421–1427, doi:10.3762/bjoc.14.119

• with allyl or propargyl bromide to obtain C12 and C13. In another way, cinchonidine was reduced by H2/Pd/C to yield dihydrocinchonidine, and then reacted with 4-trifluoromethylbenzyl bromide to obtained C14. C15 was prepared from cinchonidine via bromination, debromination and condensation with 4

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

• Anna Czarnecka,
• Emilia Kowalska,
• Agnieszka Bodzioch,
• Joanna Skalik,
• Marek Koprowski,
• Krzysztof Owsianik and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

• –CF3COOH, TMSCl/NaI failed to reduce secondary OH groups in diheteroaromatic systems and the reduction with H2/Pd/C-ZnBr2 was very slow [32]. On the other hand, some rigid diarylmethanols were successfully reduced to benzo[b]indeno[2,1-d]thiophenes using the Et3SiH–CF3COOH system which was reported in the

• tried to remove the OH group using the Pd-catalytic hydrogenolysis (Scheme 3). In case of 6b (X = S), no reaction occurred and only the substrate was recovered, most probably due to poisoning of the catalyst by the 1,3-dithianyl sulfur atoms. However, the successful catalytic hydrogenolysis (5% Pd/C) of

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

Synthetic avenues towards a tetrasaccharide related to Streptococcus pneumonia of serotype 6A

• Aritra Chaudhury,
• Mana Mohan Mukherjee and
• Rina Ghosh

Beilstein J. Org. Chem. 2018, 14, 1095–1102, doi:10.3762/bjoc.14.95

• conditions [41], followed by hydrogenation with H2/Pd-C in EtOH/EtOAc/AcOH solvent to give the deprotected tetrasaccharide 23 in 85% yield over two steps. 1H NMR in D2O of the target tetrasaccharide 23 showed the anomeric protons of the galactose, glucose, and rhamnose residues from the non-reducing end

• , 45 min; c) NaOMe, MeOH, rt; d) H2, Pd/C, EtOH/EtOAc/AcOH, rt. Optimization of protocol for the synthesis of disaccharide 3. Supporting Information Supporting Information File 145: Experimental details for the preparation of compounds 1, 3a, 4, 5, 6a, 6b, 7, 12a, 19, 20, 21, and 23 and the

The first Pd-catalyzed Buchwald–Hartwig aminations at C-2 or C-4 in the estrone series

• Ildikó Bacsa,
• Dávid Szemerédi,
• János Wölfling,
• Gyula Schneider,
• Lilla Fekete and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 998–1003, doi:10.3762/bjoc.14.85

• -13α-estrone (13). The efficient C(sp2)–N coupling method elaborated above proved to be suitable for the reaction of 2-bromo-3-benzyl ether 2 and benzophenone imine as an amine precursor (Scheme 2). The deprotection was achieved by hydrogenolysis using a Pd/C catalyst. The resulting newly-synthesized 2

A stereoselective and flexible synthesis to access both enantiomers of N-acetylgalactosamine and peracetylated N-acetylidosamine

• Bettina Riedl and
• Walther Schmid

Beilstein J. Org. Chem. 2018, 14, 856–860, doi:10.3762/bjoc.14.71

• peracetylated to yield compounds 8a and 8b. The azide function was reduced with H2 and Pd/C in acetic anhydride to gain the fully acetylated amino sugars 2a and 2b. In the final step, the compounds were deprotected using a mixture of MeOH/H2O/Et3N to yield D-GalNAc (1a) and L-GalNAc (1b). As proof of concept

• ) triethyl phosphonoacetate, NaH, DCM; b) TMSN3, Pd(PPh3)4, EtOH; c) i) DOWEX H+, MeOH; ii) O3, dimethyl sulfide, DCM/MeOH; iii) Ac2O, DMAP, pyridine; d) H2, Pd/C, Ac2O; e) MeOH/H2O/Et3N (10:10:1). Proposed mechanism of the Pd-catalyzed azide substitution of 6a in protic solvent. Approach towards

• peracetylated D-IdoNAc 2c, reactions and conditions: a) Ti(OiPr)4, t-BuOOH, D-DET, DCM; b) i) (COCl)2, DMSO, Et3N, DCM, ii) triethyl phosphonoacetate, NaH, DCM; c) TMSN3, Pd(PPh3)4, EtOH; d) i) DOWEX H+, MeOH; ii) O3, dimethyl sulfide, DCM/MeOH; iii) Ac2O, DMAP, pyridine; e) H2, Pd/C, Ac2O. Supporting

An alternative to hydrogenation processes. Electrocatalytic hydrogenation of benzophenone

• Cristina Mozo Mulero,
• Alfonso Sáez,
• Jesús Iniesta and
• Vicente Montiel

Beilstein J. Org. Chem. 2018, 14, 537–546, doi:10.3762/bjoc.14.40

• a polymer electrolyte membrane electrochemical reactor (PEMER). Palladium (Pd) nanoparticles were synthesised and supported on a carbonaceous matrix (Pd/C) with a 28 wt % of Pd with respect to carbon material. Pd/C was characterised by transmission electron microscopy (TEM), and thermogravimetric

• important to note that, formation of “active hydrogen” is the main step in this process and hydrogen-active powder electrocatalysts such as Pd/C, Pt/C or Raney-nickel have been demonstrated as the optimal choice [16][17]. Moreover, the organic molecule adsorption rate must be faster than that one associated

• water-in-oil (w/o) microemulsion (water/Brij@30/n-heptane). This methodology has been previously used in our laboratory [27][28]. We first explored the morphology, size and dispersion of Pd nanoparticles supported on Vulcan XC72R carbonaceous material (Pd/C electrocatalysts) using TEM micrographs. As

Preparation of trinucleotide phosphoramidites as synthons for the synthesis of gene libraries

• Ruth Suchsland,
• Bettina Appel and
• Sabine Müller

Beilstein J. Org. Chem. 2018, 14, 397–406, doi:10.3762/bjoc.14.28

• detritylation and coupling of the third monomer. The release of the trimer in fully protected form from the support was achieved by hydrogenation with Pd/C (10%) in tetrahydrofurane (THF) for 40 h at room temperature. Three fully protected trimers were prepared this way with isolated yields in the range of 44

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

• Lingjun Xu,
• Shuwen Han,
• Linjie Yan,
• Haifeng Wang,
• Haihui Peng and
• Fener Chen

Beilstein J. Org. Chem. 2018, 14, 309–317, doi:10.3762/bjoc.14.19

• rearrangement in 75% yield over two steps. After Pd/C-catalyzed hydrogenative deprotection of hydroxy group in methanol under acidic conditions, the corresponding alcohol 12 was transferred to the product 13 via acid-promoted deprotection. A single recrystallization from ethanol allowed 13 to be isolated with

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• -pyrazolo[3,4-d]pyrimidin-6-yl)aniline 214 by NO2 group reduction with H2, Pd/C followed by Boc protection, coupling with tributyl(3,6-dihydro-2H-pyran-4-yl)stannane (213) and subsequent Boc deprotection with TFA in DCM. Pyrazolo[3,4-d]pyrimidinylaniline 214 was used to synthesize pyrazolo[3,4-d

Gram-scale preparation of negative-type liquid crystals with a CF₂CF₂-carbocycle unit via an improved short-step synthetic protocol

• Tatsuya Kumon,
• Shohei Hashishita,
• Takumi Kida,
• Shigeyuki Yamada,
• Takashi Ishihara and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 148–154, doi:10.3762/bjoc.14.10

• compound 4a in hand, the successive hydrogenation in the presence of 20 mol % of Pd/C in methanol was performed for 1 d and generated the corresponding tetrafluorinated cyclohexane-1,4-diol 3a in quantitative yield. Compound 3a could be converted to the cyclohexadiene 1a in 82% isolated yield under the

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

The use of 4,4,4-trifluorothreonine to stabilize extended peptide structures and mimic β-strands

• Yaochun Xu,
• Isabelle Correia,
• Tap Ha-Duong,
• Nadjib Kihal,
• Jean-Louis Soulier,
• Julia Kaffy,
• Benoît Crousse,
• Olivier Lequin and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2017, 13, 2842–2853, doi:10.3762/bjoc.13.276

• with TFA and then performing the coupling reaction with Boc-L-Ala-OH in the presence of HBTU/HOBt/DIPEA or DMTMM(Cl−)/NMM. Catalytic hydrogenation, using 10% Pd/C or Pd(OH)2, under H2 atmosphere, gave pentapeptides 1a–3a in moderate to quantitative yield. After acidic removal of the Boc group, the

Regioselective decarboxylative addition of malonic acid and its mono(thio)esters to 4-trifluoromethylpyrimidin-2(1H)-ones

• Sergii V. Melnykov,
• Andrii S. Pataman,
• Yurii V. Dmytriv,
• Svitlana V. Shishkina,
• Mykhailo V. Vovk and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2017, 13, 2617–2625, doi:10.3762/bjoc.13.259

• can be converted into saturated (2-oxohexahydropyrimidin-4-yl)acetic acid derivatives by mild hydrogenation of the endocyclic C=C double bond in the presence of Pd/C as catalyst. The cis-stereoisomers selectively formed upon reduction of the Michael-type products were structurally determined by X-ray

• and a trifluoromethyl group. Thus, the acids 4a,g,i quantitatively yielded reduced products 9a–c under mild catalytic conditions (when reacted with hydrogen at atmospheric pressure and room temperature for 3 hours in the presence of 10% Pd/C catalyst) as shown in Scheme 1. The simplest acetic acid

• when the Pd/C catalyst loading is smaller than 20 weight % (otherwise the reaction proceeds too fast leading to diastereomeric mixtures with a cis- to trans-ratio of up to 3:1). The relative cis-configuration of the CF3 and CH2COOPh substituents in the prepared phenyl (2-oxo-6

A semisynthesis of 3'-O-ethyl-5,6-dihydrospinosyn J based on the spinosyn A aglycone

• Kai Zhang,
• Shenglan Liu,
• Anjun Liu,
• Hongxin Chai,
• Jiarong Li and
• Lamusi A

Beilstein J. Org. Chem. 2017, 13, 2603–2609, doi:10.3762/bjoc.13.257

• and deprotection steps. Then, with 10% Pd/C as catalyst, the 5,6-double bond of the macrolide was selectively reduced to afford 3'-O-ethyl-5,6-dihydrospinosyn J. In addition, the 3-O-ethyl-2,4-di-O-methylrhamnose is synthesized from rhamnose which is available commercially, while the D-forosamine and

• and trichloroacetonitrile with Cs2CO3 as catalyst. Finally, 3'-O-ethyl-5,6-dihydrospinosyn J was obtained through the selective hydrogenation of 12 catalyzed by 10% Pd/C. During the final reduction step, as ascertained by NMR and mass spectrometry, only the 5,6-double bond was reduced, and the other