Synthesis of modified cyclic and acyclic dextrins and comparison of their complexation ability

• Kata Tuza,
• László Jicsinszky,
• Tamás Sohajda,
• István Puskás and
• Éva Fenyvesi

Beilstein J. Org. Chem. 2014, 10, 2836–2843, doi:10.3762/bjoc.10.301

• filtrates were treated with strong ion exchanger and charcoal. Evaporation of solvents yielded 0.1/0.1/0.1 g of solids, respectively (~55%). HP-(DS~4)-cyclodextrins: Identical synthetic methods were used, as for the preparation of the corresponding acyclodextrin derivatives. DS = 4 was calculated based on

Synthesis of aromatic glycoconjugates. Building blocks for the construction of combinatorial glycopeptide libraries

• Markus Nörrlinger and
• Thomas Ziegler

Beilstein J. Org. Chem. 2014, 10, 2453–2460, doi:10.3762/bjoc.10.256

• hydrogenation of the latter with Lindlar catalyst afforded 7 almost quantitatively. Likewise, copper(I)-catalyzed 1,3-dipolar cycloaddition (Click reaction) [15][16][17][18] of 5 with Fmoc-protected propargylamine afforded first t-butyl benzoate 8 in 87% yield. Hydrogenation of the latter with Pd on charcoal

Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 1749–1758, doi:10.3762/bjoc.10.182

• charcoal are required for full conversion. We did not add acid to diminish catalyst poisoning since we were afraid of other side reactions of the complex product. In addition, the resulting products are very polar and difficult to purify. In our recent report [28] related compounds were reduced in methanol

Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocol

• Marina Caporaso,
• Giancarlo Cravotto,
• Spyros Georgakopoulos,
• George Heropoulos,
• Katia Martina and
• Silvia Tagliapietra

Beilstein J. Org. Chem. 2014, 10, 1454–1461, doi:10.3762/bjoc.10.149

• catalysts, the common Pd/C is easily handled and filtered off from the reaction mixture. It is remarkably stable under acidic and basic conditions and features a much higher surface area than alumina- and silica-supported catalysts [45]. Moreover, charcoal is rapidly heated under microwave (MW) irradiation

• selectivity (compare Table 1, entries 3 and 7). Because of the excellent dielectric properties of charcoal, we tested activated charcoal adsorbed Pd(OAc)2 and observed complete conversion and good selectivity (Table 1, entry 8). Based on this result and on a recently published study by Stahl et al. [40], it

•  1B). As depicted, Pd/C gave complete selectivity in the presence of either Na2CO3 or K2CO3, while Pd(OAc)2 was much more selective in the presence of K2CO3 when the reaction was performed in the homogeneous phase. Charcoal supported Pd(OAc)2 showed the highest selectivity with KOMe. As depicted in

Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5

• Ulrike Groenhagen,
• Michael Maczka,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2014, 10, 1421–1432, doi:10.3762/bjoc.10.146

• liquid phase is complementary and in combination allows better evaluation of the metabolic potential of an investigated microorganism. Results and Discussion The volatiles released by agar plate cultures of strain Streptomyces sp. FORM5 were collected by CLSA for one day on a charcoal filter and eluted

• pumped (MB-21E, Senior Flextronics, USA) through the closed system that contains an activated charcoal filter (Chromtech GmbH, Idstein, Precision Charcoal Filter, 5 mg) and the agar plate or liquid culture for 24 hours. The filter was then extracted by rinsing 3× with 15 µL dichloromethane (≥99.8%, Merck

A complete series of 6-deoxy-monosubstituted tetraalkylammonium derivatives of α-, β-, and γ-cyclodextrin with 1, 2, and 3 permanent positive charges

• Martin Popr,
• Simona Hybelbauerová and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2014, 10, 1390–1396, doi:10.3762/bjoc.10.142

• mixture of products with several degrees of substitution. The recently published purification procedure [16] yielded just this mixture. The purification on a column of activated charcoal was also described [28]. We found the most convenient purification method to obtain 6I-O-p-toluenesulfonyl-α

An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

• Quanxuan Zhang,
• Hong Ren and
• Gregory L. Baker

Beilstein J. Org. Chem. 2014, 10, 1365–1371, doi:10.3762/bjoc.10.139

• ), decolorized with activated charcoal and dried over anhydrous Na2SO4. The desired product diethyl α-propargyl-α-acetamidomalonate (5) was obtained as a light yellow solid [31] in 99.0% yield (122 g) by solvent evaporation and drying under vacuum. Mp 85–88 °C; 1H NMR (500 MHz, CDCl3) δ 6.91 (s, 1H), 4.24 (dd, J

Olefin cross metathesis based de novo synthesis of a partially protected L-amicetose and a fully protected L-cinerulose derivative

• Bernd Schmidt and
• Sylvia Hauke

Beilstein J. Org. Chem. 2014, 10, 1023–1031, doi:10.3762/bjoc.10.102

• ]. With a commercial sample of Pd on charcoal (10 wt %) a plethora of products was detected, four of which could be isolated and identified as the hydrogenated acetal 11, the methyl ether 13, and the two desilylated products 14 and 15 (Table 3, entry 1). Literature precedence exists for the Pd/C-induced

• dealkoxylation of acetals [65] and for desilylation reactions of silyl ethers [66]. With in situ generated Pd/C (obtained from Pd(OAc)2 and charcoal according to Felpin’s protocol) [67] an improved selectivity was observed as the cleavage of the silyl groups could be suppressed. However, reductive dealkoxylation

• of the acetal remained a problem and the combined yield of the desired products 11 and 12 was still unsatisfactory (Table 3, entry 2). This situation changed when we used Pd(OH)2 on charcoal (10 wt %) as hydrogenation catalyst, which resulted in the exclusive formation of acetal 11 and aldehyde 12 in

A novel family of (1-aminoalkyl)(trifluoromethyl)- and -(difluoromethyl)phosphinic acids – analogues of α-amino acids

• Natalia V. Pavlenko,
• Tatiana I. Oos,
• Yurii L. Yagupolskii,
• Igor I. Gerus,
• Uwe Doeller and
• Lothar Willms

Beilstein J. Org. Chem. 2014, 10, 722–731, doi:10.3762/bjoc.10.66

• after extraction of 18b water (20 mL) was added, resulting solution was decolorized with activated charcoal, filtrated and allowed to stand at 5 °C until crystallization completed, producing [(benzylamino)(phenyl)methyl](difluoromethyl)phosphinic acid (19b) as a white solid (0.32 g, 30%); mp 247 °C

Concise, stereodivergent and highly stereoselective synthesis of cis- and trans-2-substituted 3-hydroxypiperidines – development of a phosphite-driven cyclodehydration

• Peter H. Huy,
• Julia C. Westphal and
• Ari M. P. Koskinen

Beilstein J. Org. Chem. 2014, 10, 369–383, doi:10.3762/bjoc.10.35

• . However, Pd/C freshly prepared from Pd(OAc)2 and activated charcoal according to Felpin [77] delivered consistent results (reaction time < 3 h). Although the Cbz-cleavage beside a benzyl moiety in alcohols as solvent is known (for selected examples of the chemoselective Cbz-cleavage of Bn, Cbz-protected

Carbenoid-mediated nucleophilic “hydrolysis” of 2-(dichloromethylidene)-1,1,3,3-tetramethylindane with DMSO participation, affording access to one-sidedly overcrowded ketone and bromoalkene descendants^§

• Rudolf Knorr,
• Thomas Menke,
• Johannes Freudenreich and
• Claudio Pires

Beilstein J. Org. Chem. 2014, 10, 307–315, doi:10.3762/bjoc.10.28

• solution was thoroughly stirred with charcoal, then filtered, cooled in ice, and acidified with concd. hydrochloric acid. The precipitated acid 10 was extracted with Et2O or (better) pentane (3 × 70 mL). These combined extracts were repeatedly washed with distilled water to remove traces of DMSO, dried

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

• Ludovic Eberlin,
• Fabien Tripoteau,
• François Carreaux,
• Andrew Whiting and
• Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

• proved to give the best yields, probably due to the higher reactivity of the corresponding hydrazones. Furthermore, the double bond of 29 was selectively hydrogenated under palladium on charcoal, while hydrogenolysis of the hydrazine moiety occurred in the presence of Raney nickel (Scheme 22). Following

Synthesis of new enantiopure poly(hydroxy)aminooxepanes as building blocks for multivalent carbohydrate mimetics

• Léa Bouché,
• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 213–223, doi:10.3762/bjoc.10.17

• conditions using palladium on charcoal in order to remove the N-benzyl group and to cleave the N–O bond [47][48] in one step. This process is often challenging due to the difficult control of the various reaction parameters and also because of the high polarity of the newly formed compounds. According to the

• [54]. Acetic acid in methanol (1:5) was a good medium for our reductions and substrate 14 was now smoothly reduced under hydrogen atmosphere with palladium on charcoal. After filtration through a pad of acidic DOWEX® resin followed by elution with aqueous ammonia the clean poly(hydroxy)aminooxepane 26

[²H₂₆]-1-epi-Cubenol, a completely deuterated natural product from Streptomyces griseus

• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2841–2845, doi:10.3762/bjoc.9.319

• eight to ten days of incubation until fully grown, reflecting the significantly slowed metabolism due to a strong deuterium kinetic isotope effect. After full growth of the culture the volatiles emitted by S. griseus were collected on charcoal traps by use of a closed-loop stripping apparatus (CLSA) [25

• were collected by use of a closed-loop stripping apparatus (CLSA) [25]. Briefly, in a closed apparatus containing the agar plate a circulating air stream was passed over the agar plate cultures and then through a charcoal filter (Chromtech GmbH, Idstein, Germany, Precision Char Coal Filter 5 mg) for 18

Halogenated volatiles from the fungus Geniculosporium and the actinomycete Streptomyces chartreusis

• Tao Wang,
• Patrick Rabe,
• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2767–2777, doi:10.3762/bjoc.9.311

• Geniculosporium sp. 9910 were trapped on charcoal filters by using a closed-loop stripping apparatus (CLSA) [20]. After one day of collection a solvent extract of the trapped material was analysed by GC–MS. The analytical process was performed three times to demonstrate reproducibility of the results, and a

New syntheses of 5,6- and 7,8-diaminoquinolines

• Maroš Bella and
• Viktor Milata

Beilstein J. Org. Chem. 2013, 9, 2669–2674, doi:10.3762/bjoc.9.302

• method, the Skraup reaction of 3-chloroaniline led to 7-chloroquinoline which, after nitration, replacement of the chlorine atom by the amino group and catalytic hydrogenation on 5% palladium on charcoal, yielded 7,8-diaminoquinoline [10]. The preparation of 5,6-diaminoquinoline is more effective because

• recrystallisation from toluene (Scheme 1). The temperature of the chlorination (90 °C) was found to be crucial, since heating of the reaction mixture under reflux led to a rapid decomposition. The catalytic hydrogenation of 6-chloroderivative 2 using 10% palladium on charcoal or Raney nickel did not afford 7,8

• -chloroderivative 2 was performed in two successive steps. First, the reductive deselenation with SnCl2·2H2O in concentrated hydrochloric acid afforded 4-chlorodiaminoquinoline 4 in 89% yield. The subsequent catalytic hydrogenation on 10% palladium on charcoal in the absence of base, after filtration of the

A concise enantioselective synthesis of the guaiane sesquiterpene (−)-oxyphyllol

• Martin Zahel and
• Peter Metz

Beilstein J. Org. Chem. 2013, 9, 2028–2032, doi:10.3762/bjoc.9.239

• ]+. HRMS (EI) m/z: [M]+ calcd for C15H24O2, 236.1776; found, 236.1766. (−)-Oxyphyllol (1): Olefin 11 (22.9 mg, 97 μmol) and palladium on charcoal (10 wt %, 5.1 mg) were placed in a flask, and methanol (2 mL) was added. The resulting mixture was stirred under hydrogen (1 atm) for 4 h at room temperature

Synthesis of mucin-type O-glycan probes as aminopropyl glycosides

• David Benito-Alifonso,
• Rachel A. Jones,
• Anh-Tuan Tran,
• Hannah Woodward,
• Nichola Smith and
• M. Carmen Galan

Beilstein J. Org. Chem. 2013, 9, 1867–1872, doi:10.3762/bjoc.9.218

• susceptible to reduction, such as azides. After aqueous workup, the crude materials were subjected to removal of the acetyl groups using sodium hydroxide in methanol (pH = 11) followed by concomitant acetal hydrolysis and azide reduction using hydrogen and palladium on charcoal (Pd/C) in methanolic HCl (5

Synthesis of the reported structure of piperazirum using a nitro-Mannich reaction as the key stereochemical determining step

• James C. Anderson,
• Andreas S. Kalogirou,
• Michael J. Porter and
• Graham J. Tizzard

Beilstein J. Org. Chem. 2013, 9, 1737–1744, doi:10.3762/bjoc.9.200

• of resonance which would result in the formation of the E iPr group and the planar amide group during formation of 23. Reduction of the double bond with hydrogen over palladium on charcoal gave a single diastereoisomer 25 in quantitative yield. In one dimensional nOe studies irradiation of H-3 (δ

Efficient continuous-flow synthesis of novel 1,2,3-triazole-substituted β-aminocyclohexanecarboxylic acid derivatives with gram-scale production

• Sándor B. Ötvös,
• Ádám Georgiádes,
• István M. Mándity,
• Lóránd Kiss and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2013, 9, 1508–1516, doi:10.3762/bjoc.9.172

• found in the literature for the Cu(I)-catalysed flow synthesis of triazoles. Heterogeneous Cu(I) sources are most popular, such as copper-in-charcoal (Cu/C) [49][50], solid supported Cu(I) species [51][52][53][54], and heated copper wirings [55][56][57][58], but a homogeneous technique has also recently

Practical synthesis of indoles and benzofurans in water using a heterogeneous bimetallic catalyst

• Cybille Rossy,
• Eric Fouquet and
• François-Xavier Felpin

Beilstein J. Org. Chem. 2013, 9, 1426–1431, doi:10.3762/bjoc.9.160

• indoles and benzofurans in NMP and toluene, respectively. Considering that a catalyst working in water would be appealing [28], we hypothesized that activated charcoal could be a support of choice for palladium and copper due to its robustness and inertness [29][30][31][32]. In this paper we wish to

• , activated-charcoal-supported palladium catalyst for hydrogenation and debenzylation [33]. This homemade Pd/C catalyst was prepared by impregnation of activated charcoal by the reduction of Pd(OAc)2 in MeOH under an atmosphere of H2 (1 atm). With these previous results in mind, we reasoned that the

• concomitant impregnation of charcoal with palladium and copper could lead to a heterogeneous bimetallic catalyst, hopefully active for cascade Sonogashira alkynylation–cyclization sequences. Following this aim, we were pleased to find that the stirring of a mixture of Pd(OAc)2, Cu(OAc)2 and activated charcoal

Isotopically labeled sulfur compounds and synthetic selenium and tellurium analogues to study sulfur metabolism in marine bacteria

• Nelson L. Brock,
• Christian A. Citron,
• Claudia Zell,
• Martine Berger,
• Irene Wagner-Döbler,
• Jörn Petersen,
• Thorsten Brinkhoff,
• Meinhard Simon and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 942–950, doi:10.3762/bjoc.9.108

• volatiles on charcoal [25]. The substrate scope of the involved enzymatic machinery was tested in feeding experiments with DMSeP, which is produced by the salt marsh cordgrass Spartina alternifolia amended with selenate [26], and the non-natural analogue DMTeP. DMSeP was effectively metabolized to give

Simple synthesis of pyrrolo[3,2-e]indole-1-carbonitriles

• Adam Trawczyński,
• Robert Bujok,
• Zbigniew Wróbel and
• Krzysztof Wojciechowski

Beilstein J. Org. Chem. 2013, 9, 934–941, doi:10.3762/bjoc.9.107

• (100 mg, 0.26 mmol), ammonium formate (0.16 g, 10 mmol) and 10% palladium on charcoal (90 mg) were suspended in isopropanol (5 mL), flushed with argon for 5 min and then heated in a sealed tube at 95 °C overnight. Then the reaction mixture was passed through Celite, washed with dichloromethane–methanol

Synthesis and stability study of a new major metabolite of γ-hydroxybutyric acid

• Ida Nymann Petersen,
• Jesper Langgaard Kristensen,
• Christian Tortzen,
• Torben Breindahl and
• Daniel Sejer Pedersen

Beilstein J. Org. Chem. 2013, 9, 641–646, doi:10.3762/bjoc.9.72

• bromide 10 and alcohol 7. With no further purification the mixture was dissolved in MeOH (19 mL) and Pd on activated charcoal (10% w/w, 20 mg) was added, and then the flask was fitted with a H2 balloon and stirred vigorously. After 24 h the mixture was filtered through a pad of Celite and concentrated in

Synthesis of chiral sulfoximine-based thioureas and their application in asymmetric organocatalysis

• Marcus Frings,
• Isabelle Thomé and
• Carsten Bolm

Beilstein J. Org. Chem. 2012, 8, 1443–1451, doi:10.3762/bjoc.8.164

• reduce the α-nitro group of (R)-7 to the corresponding amino substituent (as in (R)-8) failed [58]. None of the reductive conditions, which included (1) hydrogenation over palladium/charcoal, (2) applying samarium diiodide with methanol as proton source, and (3) using a combination of zinc powder with