Synthesis of novel 13α-estrone derivatives by Sonogashira coupling as potential 17β-HSD1 inhibitors

• Ildikó Bacsa,
• Rebeka Jójárt,
• János Wölfling,
• Gyula Schneider,
• Bianka Edina Herman,
• Mihály Szécsi and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2017, 13, 1303–1309, doi:10.3762/bjoc.13.126

• semihydrogenation of internal alkynes may be achieved by two main catalytic methods: with molecular hydrogen using Lindlar’s catalyst [25][26] or by transfer hydrogenation with hydrogen donors [27][28]. Additionally, alkynes undergo reduction with diimide to produce cis-alkenes [29]. Li et al. carried out the

• . Conclusion In conclusion, we described here an efficient synthetic microwave procedure for the synthesis of novel phenylalkynyl derivatives of 13α-estrone (1) and its 3-methyl ether 2. The steroidal alkynes were chemo- and stereoselectively hydrogenated by transfer hydrogenation in a microwave reactor

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

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

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• -doped mesoporous titania film (95% sel. at 30% conversion, 323 K) [150] (Table 1, entries 31–33). The reduction of 7 to 7a was also reported by transfer hydrogenation using formic acid / triethylamine as hydrogen source and packed Au@TiO2 (rutile) catalyst [151]. An outstanding 99.7% yield was achieved

NMR reaction monitoring in flow synthesis

• M. Victoria Gomez and
• Antonio de la Hoz

Beilstein J. Org. Chem. 2017, 13, 285–300, doi:10.3762/bjoc.13.31

• concentrations of 1 mmol L−1 in single-scan experiments. As a proof-of-concept, they studied the transfer hydrogenation process of acetophenone with isopropanol catalysed by iridium complexes. The reaction was performed in batch and the sample was introduced into the magnet with a pump and Teflon tubing to form

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• ]. Opatz et al. developed the enantioselective syntheses of various alkaloids using the rhodium catalyst developed by Noyori [88] for the asymmetric transfer hydrogenation of imines. Interestingly, imines are formed from unstable α-aminonitrile intermediates which spontaneously eliminate HCN [89][90][91

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• as potential catalysts, and chiral catalyst L25 was identified as the catalyst of choice. Although no chirality transfer was observed during the reduction of 2-phenylquinoline, L25 was found to be a very active catalyst promoting transfer hydrogenation of a C=N group containing heterocycles and

• bond to carbonyl [80]. Transfer hydrogenation of phenylquinolines catalyzed by haloperfluoroalkanes by Bolm and co-workers [81]. Halogen bond activation of benzhydryl bromides by Huber and co-workers [82]. Halogen bond-donor-catalyzed addition to oxocarbenium ions by Huber and co-workers [89]. Halogen

• bond-donor activation of α,β-unsaturated carbonyl compounds in the [2 + 4] cycloaddition reaction of MVK and cyclopentadiene [88]. Halogen bond donor activation of imines in the [2 + 4] cycloaddition reaction of imine and Danishefsky’s diene [90]. Transfer hydrogenation catalyzed by a chiral halogen

Reactivity studies of pincer bis-protic N-heterocyclic carbene complexes of platinum and palladium under basic conditions

• David C. Marelius,
• Curtis E. Moore,
• Arnold L. Rheingold and
• Douglas B. Grotjahn

Beilstein J. Org. Chem. 2016, 12, 1334–1339, doi:10.3762/bjoc.12.126

• converted in situ to the hydride and isolated, or generated in situ and used as a transfer hydrogenation catalyst. Interestingly, the ligand substitution rate of ethylene and the heterolysis of dihydrogen was much greater for 3 than for 2. With only a few papers exploring the utility of these imidazol-2-yl

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• disulfides and sulfides, which are involved in the synthesis of ligands and pharmaceutical chiral synthetic precursors [1][2] and in (b) the transfer-hydrogenation reaction catalyzed by bifunctional chiral ruthenium complexes, employed in the synthesis of peptide mimics with an interesting

Synthesis and structures of ruthenium–NHC complexes and their catalysis in hydrogen transfer reaction

• Chao Chen,
• Chunxin Lu,
• Qing Zheng,
• Shengliang Ni,
• Min Zhang and
• Wanzhi Chen

Beilstein J. Org. Chem. 2015, 11, 1786–1795, doi:10.3762/bjoc.11.194

• molecular structures of the complexes 4 and 5 were also studied by X-ray diffraction analysis. These ruthenium complexes have proven to be efficient catalysts for transfer hydrogenation of various ketones. Keywords: N-heterocyclic carbene; ruthenium; transfer hydrogenation; Introduction N-Heterocyclic

• complexes show good catalytic activity in the transfer hydrogenation of ketones. The reaction of acetonitrile-coordinated Ru–NHC complex 2 with other donors such as triphenylphosphine and 1,10-phenanthroline was also studied. Results and Discussion Synthesis and characterization of [Ru(L1)2(CH3CN)2](PF6)2

• 2.028 Å) and the Ru–C (1.947 Å) is shorter than that of many known Ru–Ccarbene distances [17][18][19][20][21][22][23][24][25][26][27][28][29]. Catalytic transfer hydrogenation reaction Ruthenium–NHC complexes are known to be efficient catalysts for transfer hydrogenation reactions [23][37][38][39]. The

The enantioselective synthesis of (S)-(+)-mianserin and (S)-(+)-epinastine

• Piotr Roszkowski,
• Jan. K. Maurin and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2015, 11, 1509–1513, doi:10.3762/bjoc.11.164

• /bjoc.11.164 Abstract A simple enantioselective synthetic procedure for the preparation of mianserin and epinastine in optically pure form is described. The key step in the synthetic pathway is the asymmetric reduction of the cyclic imine using asymmetric transfer hydrogenation conditions. Keywords

• phthalimide proposed by Moffett [15] may be used for this step with comparable results. The imine 6 was then transformed to the enantiomerically enriched amine 7 with the aid of asymmetric transfer hydrogenation (ATH) process [8][10][11]. As in our synthesis of aptazepine [8], we initially used the chiral

• )-(+)-epinastine. Chirality was introduced in a key step by asymmetric transfer hydrogenation. This synthetic procedure could be used for the preparation of other compounds variously substituted at the aryl rings. The structure of mianserin 1 and epinastine 2. Catalysts used in ATH. The ORTEP diagram for X-ray

Versatile synthesis of amino acid functionalized nucleosides via a domino carboxamidation reaction

• Vicky Gheerardijn,
• Jos Van den Begin and
• Annemieke Madder

Beilstein J. Org. Chem. 2014, 10, 2566–2572, doi:10.3762/bjoc.10.268

• of the pyrimidine double bond, transfer hydrogenation with cyclohexene as hydrogen source and 10% palladium on carbon should be used [60][61][62]. As the methyl ester derivative of the amino acid is commercially available but rather expensive, we performed the esterification reaction on the benzyl

Stereoselective synthesis of carbocyclic analogues of the nucleoside Q precursor (PreQ₀)

• Sabin Llona-Minguez and
• Simon P. Mackay

Beilstein J. Org. Chem. 2014, 10, 1333–1338, doi:10.3762/bjoc.10.135

• configuration [44]. Mesylation of 26 and 27 lead to intermediates 28 and 29 [45], which were subsequently reacted with sodium azide inverting the stereochemistry as required [46]. A final transfer hydrogenation of 30 and 31 yielded the desired amines rapidly and with excellent yields [47]. Amines 23 and 24 were

Unusual polymorphism in new bent-shaped liquid crystals based on biphenyl as a central molecular core

• Anna Kovářová,
• Svatopluk Světlík,
• Václav Kozmík,
• Jiří Svoboda,
• Vladimíra Novotná,
• Damian Pociecha,
• Ewa Gorecka and
• Natalia Podoliak

Beilstein J. Org. Chem. 2014, 10, 794–807, doi:10.3762/bjoc.10.75

• phenols 3–5 in the presence of N,N'-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP) to yield esters 11–13 (Scheme 1). The methoxycarbonyl group in 11 was subsequently removed by means of aq. ammonia and the benzyl group in 12 and 13 by a palladium-catalysed transfer-hydrogenation. The

A catalyst-free multicomponent domino sequence for the diastereoselective synthesis of (E)-3-[2-arylcarbonyl-3-(arylamino)allyl]chromen-4-ones

• Pitchaimani Prasanna,
• Pethaiah Gunasekaran,
• Subbu Perumal and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2014, 10, 459–465, doi:10.3762/bjoc.10.43

• –Hilman condensation, and a final deoxygenation. The deoxygenation is assumed to be induced by carbon monoxide resulting from the thermal decomposition of the dimethylformamide solvent. Keywords: chromones; domino reactions; Michael additions; multicomponent reactions; transfer hydrogenation

A combined continuous microflow photochemistry and asymmetric organocatalysis approach for the enantioselective synthesis of tetrahydroquinolines

• Erli Sugiono and
• Magnus Rueping

Beilstein J. Org. Chem. 2013, 9, 2457–2462, doi:10.3762/bjoc.9.284

• Erli Sugiono Magnus Rueping Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, D-52074 Aachen, Germany 10.3762/bjoc.9.284 Abstract A continuous-flow asymmetric organocatalytic photocyclization–transfer hydrogenation cascade reaction has been developed. The new protocol allows

• dihydropyridine as hydrogen source providing the desired products in good yields and with excellent enantioselectivities. Keywords: asymmetric transfer hydrogenation; binolphosphate; continuous-flow reactors; flow chemistry; microreactors; organocatalysis; photochemistry; Introduction Tetrahydroquinolines [1][2

• hand, the substrate scope of this new photocyclization–asymmetric transfer hydrogenation sequence was examined. The results are summarized in Table 2. In general, different 2-aminochalcones bearing substituted aromatic residues on both ketone and enone moieties underwent the desired photocyclization

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• 1.84 as the nucleophile has been successfully conducted (Scheme 15) [49]. The nitrile unit is partially reduced and hydrolysed to the benzaldehyde 1.71 using Raney-Ni under transfer hydrogenation conditions in wet formic acid. A Darzens reaction between this aldehyde and ethyl chloroacetate in the

Straightforward synthesis of a tetrasaccharide repeating unit corresponding to the O-antigen of Escherichia coli O16

• Manas Jana and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 1757–1762, doi:10.3762/bjoc.9.203

• transfer hydrogenation with triethylsilane and 10% Pd/C [20]; (b) an acetylation using acetic anhydride and pyridine, and (c) a saponification reaction with sodium methoxide to furnish compound 1, which was purified over a Sephadex® LH-20 gel to give the pure compound 1 in 64% overall yield. The structure

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

• Rahat Javaid,
• Shin-ichiro Kawasaki,
• Akira Suzuki and
• Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

• catalyzed with core–shell Au–Pd NPs and Au NPs [23][24][25][26]. Formic acid is another attractive H2 source because it is safe, easy to handle, and requires no high-pressure equipment. Formic acid and formate have been used as effective H2 donors in the catalytic transfer hydrogenation of aromatic nitro

• Pd site per hour) at 40 °C. This value is much higher than those reported for the catalytic transfer hydrogenation of p-nitrophenol and benzyl acetate in a flow system [30][32]. We conducted the reaction while changing the concentration of formic acid and maintaining the p-nitrophenol concentration

• ]. Consequently, we concluded that the nitro group was reduced in a transfer hydrogenation process and not by molecular H2 generated from the dehydrogenation of formic acid. In contrast to hydrogenation using gaseous H2, the present system using formic acid as hydrogen donor has the advantages of convenience and

Aqueous reductive amination using a dendritic metal catalyst in a dialysis bag

• Jorgen S. Willemsen,
• Jan C. M. van Hest and
• Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2013, 9, 960–965, doi:10.3762/bjoc.9.110

• related iridium complexes that are capable of performing transfer hydrogenation reactions, as has been documented by Fukuzumi et al. [28][29][30]. The water-soluble iridium catalyst 3 was prepared according to a procedure of Francis in high yield (Scheme 1) [27]. The starting material is [Cp*IrCl2]2 which

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

• °C) led to a mixture of the expected product 9a and the product 10a in that the cyano group was reduced to a methyl substituent (Scheme 4). There is a literature precedence [19] for similar transformations of cyanoarenes into corresponding methyl derivatives upon transfer hydrogenation with ammonium

Glycosylation efficiencies on different solid supports using a hydrogenolysis-labile linker

• Mayeul Collot,
• Steffen Eller,
• Markus Weishaupt and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 97–105, doi:10.3762/bjoc.9.13

• -transfer-hydrogenation conditions proved to be very efficient for both deprotection and cleavage of the peptide from the solid support [38]. In this context, in situ generation of palladium black by reduction of palladium(II) acetate with ammonium formate in DMF yielded the best results. Although

Removal of benzylidene acetal and benzyl ether in carbohydrate derivatives using triethylsilane and Pd/C

• Abhishek Santra,
• Tamashree Ghosh and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 74–78, doi:10.3762/bjoc.9.9

• achieved under catalytic transfer hydrogenation conditions by using a combination of triethylsilane and 10% Pd/C in CH3OH at room temperature. A variety of carbohydrate diol derivatives were prepared from their benzylidene derivatives in excellent yield. Keywords: benzylidene; glycoside; Pd/C; transfer

• development of a mild, neutral reaction condition for the removal of benzylidene acetals would be useful in the derivatization of a carbohydrate framework. Mandal et al. reported the removal of benzyl esters/ethers and the reduction of alkenes/alkynes by catalytic transfer hydrogenation using a combination

• acetal and O-benzyl groups under catalytic transfer hydrogenation conditions has been developed by using a combination of triethylsilane and 10% Pd/C. The efficacy of this methodology is comparable to the conventional hydrogenation involving hydrogen gas and Pd/C, whereas it does not require handling of

Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part II: Iridomyrmecins

• Robert Hilgraf,
• Nicole Zimmermann,
• Lutz Lehmann,
• Armin Tröger and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1256–1264, doi:10.3762/bjoc.8.141

• between the methyl group at C-7 and the substitution pattern at C-7a and C-4a, respectively) configured iridomyrmecins. Key steps were two stereoselective hydrogenations: A transfer hydrogenation for a formal “anti” delivery of hydrogen [14][15], as represented in 5, and the use of Crabtree’s catalyst in

• dihydronepetalactones [1], this key intermediate could be obtained via a highly diastereoselective transfer hydrogenation of the known [19] trisubstituted cyclopentene 7 with ammonium formate over palladium [1][14][15]. Starting from the aldehyde 8, the relative configuration of which had been confirmed by NOE

• hydrogenations: A transfer hydrogenation for a formal “anti” delivery of hydrogen and the use of Crabtree’s catalyst in a directed hydrogenation for a “syn”-addition of hydrogen. Starting from pure enantiomers of limonene [1] these novel synthetic routes provided iridomyrmecins A, A' and B, B' in 2–3% yield over

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

• Magnus Rueping,
• Teerawut Bootwicha and
• Erli Sugiono

Beilstein J. Org. Chem. 2012, 8, 300–307, doi:10.3762/bjoc.8.32

• example of a continuous-flow organocatalytic asymmetric transfer hydrogenation performed in a microreactor. In this work a ReactIR flow cell was coupled with the microreactor and applied as an inline monitoring device for optimizing the reactions. Results and Discussion The continuous-flow microreactor

• to determine the optimum reaction conditions. The IR spectra were recorded at predefined intervals and the raw data were analysed with iC-IR analysis software. The first reaction examined the asymmetric organocatalytic transfer hydrogenation [97][98][99][100][101] of benzoxazine 3a in the presence of

• -withdrawing or electron-donating groups can be reduced in a continuous fashion and the products 4 were isolated in good yields and with excellent enantioselectivities. Encouraged by the results, we next studied the transfer hydrogenation of quinolines 5 [103][104][105][106]. The optimum reaction temperature

α,β-Aziridinylphosphonates by lithium amide-induced phosphonyl migration from nitrogen to carbon in terminal aziridines

• David. M. Hodgson and
• Zhaoqing Xu

Beilstein J. Org. Chem. 2010, 6, 978–983, doi:10.3762/bjoc.6.110

• absence of an N-substituent, cis-β-alkyl-substituted aziridinylphosphonates give β-aminophosphonates [32] and we observed that trans-β-alkyl-substituted aziridinylphosphonate (–)-3k underwent completely regioselective hydrogenolysis under transfer hydrogenation conditions [31] to produce β

Formation of epoxide-amine oligo-adducts as OH-functionalized initiators for the ring-opening polymerization of ε-caprolactone

• Julia Theis and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 938–944, doi:10.3762/bjoc.6.105

• catalytic transfer hydrogenation. Accordingly, 4-nitroanisole was reduced under microwave conditions to give 4-aminoanisole which reacted immediately with the diglycidyl ether of bisphenol A in an addition polymerization reaction to yield oligo(amino alcohol)s. The hydroxy groups of the new formed oligomers

• were used as the initiator for the ring-opening polymerization of ε-caprolactone to produce a graft copolymer. Keywords: addition oligomerization; epoxide-amine adducts; microwave; ring-opening polymerization; transfer hydrogenation; Introduction In the last decade the use of microwave (MW

• former work on the formation of hyperbranched epoxide-amine adducts via microwave-assisted heterogeneous catalytic transfer hydrogenation [22], we report herein the synthesis of an linear oligo(amino alcohol). The hydroxy groups of the latter were then used as an initiator for the ring-opening