cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin

• Dimpee Gogoi,
• Runjun Devi,
• Pallab Pahari,
• Bipul Sarma and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280

• using 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as reaction medium as well as the reaction promoter. The first choice of HFIP was based on its recently found ability to promote high-yielding IFCEA cyclization of benzylic epoxides [29]. Unfortunately, however, refluxing a solution of (±)-6a in HFIP for 4

Electron-transfer-initiated benzoin- and Stetter-like reactions in packed-bed reactors for process intensification

• Anna Zaghi,
• Daniele Ragno,
• Graziano Di Carmine,
• Carmela De Risi,
• Olga Bortolini,
• Pier Paolo Giovannini,
• Giancarlo Fantin and
• Alessandro Massi

Beilstein J. Org. Chem. 2016, 12, 2719–2730, doi:10.3762/bjoc.12.268

• -supported base. Together with the ease of product/promoter separation, an important benefit of the flow regime has been the significant long-term stability of the packing bed (ca. 5 five days on streams). Small-scale reactors have been described in this work; nevertheless, an easy scale-up of the disclosed

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• -dicarbonyl compounds with both cyclic and acyclic Morita–Baylis–Hillman (MBH) alcohols, using Et3B as a Lewis acid promoter, is described herein. A wide range of the corresponding functionalized allylated derivatives have been obtained in good yields and with high selectivity. Keywords: allylic substitution

• -enone (1a) and acyclic ethyl 2-(hydroxymethyl)acrylate (1b), under the action of 1,3-dicarbonyl compounds 2, in the presence of an appropriate palladium catalyst and Et3B as a Lewis acid promoter, into the allylation compounds 3–8 with the formation of only water as a byproduct. These derivatives can be

• ], which further gives, in the presence of Pd(0), the π-allylpalladium complex I2. This intermediate reacts then with the diethyl malonate carbanion I3, in situ formed, to generate the promoter Et3B of this nucleophilic allylic substitution and the desired allylated product 3a. Next, under the previously

TMSBr-mediated solvent- and work-up-free synthesis of α-2-deoxyglycosides from glycals

• Mei-Yuan Hsu,
• Yi-Pei Liu,
• Sarah Lam,
• Su-Ching Lin and
• Cheng-Chung Wang

Beilstein J. Org. Chem. 2016, 12, 1758–1764, doi:10.3762/bjoc.12.164

• under ambient atmosphere (Table 1, α:β = 2:1, entry 1). Without work-up and washing, S-2-deoxyglycoside 2 could be directly isolated and purified by flash column chromatography. We further extended the scope of the reaction to other glycals by using TMSBr as the promoter under neat conditions (Table 1

Rh-Catalyzed reductive Mannich-type reaction and its application towards the synthesis of (±)-ezetimibe

• Motoyuki Isoda,
• Kazuyuki Sato,
• Yurika Kunugi,
• Satsuki Tokonishi,
• Atsushi Tarui,
• Masaaki Omote,
• Hideki Minami and
• Akira Ando

Beilstein J. Org. Chem. 2016, 12, 1608–1615, doi:10.3762/bjoc.12.157

• asymmetric Mannich reaction using a Lewis acid catalyst [1]. (L)-Proline is known as an excellent promoter for the Mannich reaction [2][3][4][5][6], and besides this, the reaction of the silyl enol ether derivatives with imines was used as an effective method [7][8][9]. In this situation, a wide variety of

Antibiotics from predatory bacteria

• Juliane Korp,
• María S. Vela Gurovic and
• Markus Nett

Beilstein J. Org. Chem. 2016, 12, 594–607, doi:10.3762/bjoc.12.58

• regulatory proteins influencing the transcription by binding to a specific enhancer-like element (ELE) sequence located in close vicinity to the corresponding promoter in a δ54 dependent manner [83]. Two EBPs of M. xanthus DK1622, namely HsfA and MXAN4899, have recently been identified as transcriptional

• transcription [106]. During early stages of transcriptional initiation, the RNAP clamp possesses an opened form in order to allow binding of the promoter DNA to the active-center cleft. At late transcriptional initiation and elongation, the clamp changes into a closed position to retain the DNA inside the

A selective and mild glycosylation method of natural phenolic alcohols

• Mária Mastihubová and
• Monika Poláková

Beilstein J. Org. Chem. 2016, 12, 524–530, doi:10.3762/bjoc.12.51

• by the reduction of the corresponding acetylated aldehydes or acids. Various stereoselective 1,2-trans-O-glycosylation methods were studied, including the DDQ–iodine or ZnO–ZnCl2 catalyst combination. Among them, ZnO–iodine has been identified as a new glycosylation promoter and successfully applied

• look for milder conditions for an efficient and inexpensive method of glycosylation while excluding the use of toxic mercury salts as promoter (Helferich reaction) or silver salts. The latter are often rather expensive, moisture and light sensitive, and uncomfortable to handle. Accordingly, various

• 6a–c, 9 and 12 (Scheme 3, Table 1). The choice of the glycosylation promoter was strongly limited by the instability of the phenolic acetyl group under basic as well as strongly acidic conditions. Only mild, neutral promoters were therefore selected and investigated. Thus, the reactions were

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

• biologically interesting β-amino acid derivatives (Table 2) [42]. In this work, the authors compared the results achieved by means of 4 with other urea- and thiourea-based organocatalysts in order to understand the effect of the acidity, the structural rigidity, and the bifunctionality of the promoter. These

Recent highlights in biosynthesis research using stable isotopes

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2015, 11, 2493–2508, doi:10.3762/bjoc.11.271

• promoter exchange [45] in the native host. Bioinformatics allowed for the annotation of several epimerization domains in the kollosin A NRPS, but it is hard to determine the actual activity of each of these functions. To overcome this problem, L-[2H8]valine, L-[2H10]leucin, L-[2H7,15N]tyrosine und L

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• useful method for the synthesis of aromatic secondary thioamides [1][2][3][4][5][6]. Our group [7] and others [8] have recently described an efficient modification of this method by using trifluoromethanesulfonic (triflic) acid as a promoter. Furthermore, we reported a simple procedure for the oxidative

Synthesis of constrained analogues of tryptophan

• Elisabetta Rossi,
• Valentina Pirovano,
• Marco Negrato,
• Giorgio Abbiati and
• Monica Dell’Acqua

Beilstein J. Org. Chem. 2015, 11, 1997–2006, doi:10.3762/bjoc.11.216

• -acetamidoacrylate (2) and its congeners with cyclic/acyclic dienes and azadienes occur under conventional heating or microwave irradiation [24]. Moreover, the use of titanium tetrachloride as Lewis acidic promoter has been reported [25]. Finally, simple functionalization reactions of indoles with 2 are reported in

• intermolecular [4 + 2]-cycloaddition of 2-vinylindoles and methyl 2-acetamidoacrylate. Although the reaction requires a stoichiometric amount of EtAlCl2 as promoter, it presents several advantages with respect to classical Fischer indole synthesis, normally adopted for the preparation of these derivatives [11

• of these compounds. In particular, the dependence upon the substitution pattern at nitrogen and at the outer-ring double bond, highlighted the need to select the appropriate promoter for each desired transformation. Examples of drugs embodying unnatural amino acids. Examples of biologically active

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

• Mohamed Ramadan El Sayed Aly,
• Hosam Ali Saad and
• Shams Hashim Abdel-Hafez

Beilstein J. Org. Chem. 2015, 11, 1922–1932, doi:10.3762/bjoc.11.208

• ] was coupled with cholest-5-en-3β-ol (1) as glycosyl acceptor in the presence of catalytic TMSOTf as promoter to afford 15 in 74% yield. The large anomeric coupling constant (J1,2 = 8.4 Hz) of the pyranoside moiety at δ = 5.30 ppm ensured the β-configuration of this glycoside. Deacetylation of

Engineering Pichia pastoris for improved NADH regeneration: A novel chassis strain for whole-cell catalysis

• Martina Geier,
• Christoph Brandner,
• Gernot A. Strohmeier,
• Mélanie Hall,
• Franz S. Hartner and
• Anton Glieder

Beilstein J. Org. Chem. 2015, 11, 1741–1748, doi:10.3762/bjoc.11.190

• single knock-out strains, respectively. The behavior of the das knock-out strains in heterologous protein production was tested by expressing green fluorescent protein (GFP) under the control of the AOX1 promoter (PAOX1), which is the most prominent, methanol inducible promoter for P. pastoris. A

• Vogl (TU Graz, Austria) for providing the plasmid harboring the coding sequence of GFP under the control of the AOX1 promoter. The research leading to these results has received funding from the Innovative Medicines Initiative Joint Undertaking project CHEM21 under grant agreement n°115360, resources

The facile construction of the phthalazin-1(2H)-one scaffold via copper-mediated C–H(sp²)/C–H(sp) coupling under mild conditions

• Wei Zhu,
• Bao Wang,
• Shengbin Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2015, 11, 1624–1631, doi:10.3762/bjoc.11.177

• the impact of various inorganic bases and K2CO3 proved to be the most efficient promoter (Table 1, entries 1–7). The subsequent evaluation of copper salts revealed that Cu(OAc)2 gave the best yield (Table 1, entries 8–11). The effect of different solvents on the transformation was also investigated

N-Alkyl derivatives of diosgenyl 2-amino-2-deoxy-β-D-glucopyranoside; synthesis and antimicrobial activity

• Agata Walczewska,
• Daria Grzywacz,
• Dorota Bednarczyk,
• Małgorzata Dawgul,
• Andrzej Nowacki,
• Wojciech Kamysz,
• Beata Liberek and
• Henryk Myszka

Beilstein J. Org. Chem. 2015, 11, 869–874, doi:10.3762/bjoc.11.97

• -hydroxy derivatives of D-glucose and L-rhamnose [49]. Glycosylation of diosgenin with twelve different derivatives of D-glucosamine (2a–d, 3a–d, and 5a–d), was examined using “normal” and “reverse” procedures [50] (Table 1). In the “normal” procedure, the promoter (silver triflate or trimethylsilyl

• triflate) was added to the solution of diosgenin and the respective glycosyl donor. In the “reverse” procedure, the respective glycosyl donor was added to the solution of diosgenin and the promoter. Diosgenin glycosylations were carried out in dichloromethane or/and in a mixture of dichloromethane and

Synthesis of a hexasaccharide partial sequence of hyaluronan for click chemistry and more

• Marina Bantzi,
• Stephan Rigol and
• Athanassios Giannis

Beilstein J. Org. Chem. 2015, 11, 604–607, doi:10.3762/bjoc.11.67

• ][23] was linked with glycosyl acceptor 2 [24][25] using TMSOTf as promoter to obtain disaccharide 4 in 90% yield. Likewise, reaction of glycosyl donor 1 with monosaccharide 3 [26] and subsequent O-TBS group cleavage with Olah's reagent [27], afforded disaccharide 5 in 86% yield. Thence, both

Morita–Baylis–Hillman reaction of acrylamide with isatin derivatives

• Radhey M. Singh,
• Kishor Chandra Bharadwaj and
• Dharmendra Kumar Tiwari

Beilstein J. Org. Chem. 2014, 10, 2975–2980, doi:10.3762/bjoc.10.315

• Abstract The Morita–Baylis–Hillman reaction of acrylamide, as an activated alkene, has seen little development due to its low reactivity. We have developed the reaction using isatin derivatives with acrylamide, DABCO as a promoter and phenol as an additive in acetonitrile. The corresponding aza version

A comparative study of the interactions of cationic hetarenes with quadruplex-DNA forming oligonucleotide sequences of the insulin-linked polymorphic region (ILPR)

• Darinka Dzubiel,
• Heiko Ihmels,
• Mohamed M. A. Mahmoud and
• Laura Thomas

Beilstein J. Org. Chem. 2014, 10, 2963–2974, doi:10.3762/bjoc.10.314

• that consists of repetitive DNA units with varying length and sequence [1]. The ILPR is located in the promoter region of the human insulin gene and is proposed to control the expression of the latter. It was shown that insulin-dependent diabetes mellitus (IDDM, type-I diabetes) is associated with the

• observation that insulin associates with quadruplex DNA [10]. In particular, it was assumed that the formation of quadruplex structures affects the transcriptional activity, because the position of the ILPR in the promoter region of the gene represents a stake close to the transcription process [9][11][12

Galactan synthesis in a single step via oligomerization of monosaccharides

• Marius Dräger and
• Amit Basu

Beilstein J. Org. Chem. 2014, 10, 2658–2663, doi:10.3762/bjoc.10.279

• the donor to a solution of 3 and La(ClO4)3 might reduce self-oligomerization. However, addition of 2 via a syringe pump did not significantly improve the yields, nor did it shift the product distribution to longer oligomers. The use of La(ClO4)3 as the promoter appears to be critical in this reaction

• did not result in any significant changes (Table 1, entry 7). Finally, the use of Hf(OTf)4 as a promoter [24] was completely ineffective and no glycosylation was observed (Table 1, entry 8). Carrying out the reaction in the absence of base did not have a significant effect, although it minimally

A general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes

• Shekaraiah Devari,
• Manjeet Kumar,
• Ramesh Deshidi,
• Masood Rizvi and
• Bhahwal Ali Shah

Beilstein J. Org. Chem. 2014, 10, 2649–2653, doi:10.3762/bjoc.10.277

• , India 10.3762/bjoc.10.277 Abstract A novel metal-free strategy for a rapid and α-selctive C-alkynylation of glycals was developed. The reaction utilizes TMSOTf as a promoter to generate in situ trimethylsilylacetylene for C-alkynylation. Thanks to this methodology, we can access C-glycosides in a

• characterized by a requirement of pre-formed trimethylsilylacetylene. Results and Discussion Initial investigations involved the use of 3,4,6-tri-O-acetyl-D-glucal (1) and phenylacetylene (2) as model substrates with TMSOTf as a promoter within DCM at −20 °C. To our delight TLC showed full consumption of the

Autonomous assembly of synthetic oligonucleotides built from an expanded DNA alphabet. Total synthesis of a gene encoding kanamycin resistance

• Kristen K. Merritt,
• Kevin M. Bradley,
• Daniel Hutter,
• Mariko F. Matsuura,
• Diane J. Rowold and
• Steven A. Benner

Beilstein J. Org. Chem. 2014, 10, 2348–2360, doi:10.3762/bjoc.10.245

• fragments. The product of the autonomous assembly was then ligated behind a β-galactosidase promoter in a plasmid containing a gene conferring resistance to ampicillin. This was used to transform E. coli cells, which were found to grow in medium containing kanamycin. Plating experiments quantitated these

• µg/mL) and IPTG (1 mM). Single colonies were then used to inoculate cultures grown in the presence of ampicillin alone. Plasmids were harvested with the Zyppy™ Miniprep kit (Zymo Research) and were sent out to be sequenced with vector primers (T7 Terminator and T7 Promoter long). The sequences

• transformed by plasmids containing the self-assembled kanamycin-resistance gene placed behind a β-galactosidase promoter in the TOPO expression vector (Invitrogen), but without selection for resistance to kanamycin. (a) The cell culture was diluted in two steps by a factor of 267,000. Then, aliquots (25 µL

Facile synthesis of 1H-imidazo[1,2-b]pyrazoles via a sequential one-pot synthetic approach

• András Demjén,
• Márió Gyuris,
• János Wölfling,
• László G. Puskás and
• Iván Kanizsai

Beilstein J. Org. Chem. 2014, 10, 2338–2344, doi:10.3762/bjoc.10.243

• of 59% during a reaction time of 15 min when a catalytic amount of HClO4 (20 mol %) was used as GBB-3CR promoter [7] in EtOH. 1D- and 2D NMR techniques (1H,13C-HSQC, 1H,13C-HMBC, 1H,1H-COSY and 1H,1H-NOESY) confirmed the exclusive presence of a 1H-imidazo[1,2-b]pyrazole core with an endocyclic double

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

• -substituted 1,2-oxazines to bicyclic ketones has been described in many examples [24]. Gratifyingly, starting from 1,2-oxazine 4 with tin(IV) chloride as Lewis acidic promoter the corresponding ketone was obtained in excellent stereoselectivity. The subsequent protection of the primary hydroxy group as TBS

Asymmetric Ugi 3CR on isatin-derived ketimine: synthesis of chiral 3,3-disubstituted 3-aminooxindole derivatives

• Giordano Lesma,
• Fiorella Meneghetti,
• Alessandro Sacchetti,
• Mattia Stucchi and
• Alessandra Silvani

Beilstein J. Org. Chem. 2014, 10, 1383–1389, doi:10.3762/bjoc.10.141

• upon adding MgBr2, even though this promoter was shown to perform well in other reactions on ketimine 1. Evidently, in this case, the effective protonation of the nitrogen would be required in order to efficiently carry out the attack of the moderately nucleophilic isonitrile. An increase of the

Glycosystems in nanotechnology: Gold glyconanoparticles as carrier for anti-HIV prodrugs

• Fabrizio Chiodo,
• Marco Marradi,
• Javier Calvo,
• Eloisa Yuste and
• Soledad Penadés

Beilstein J. Org. Chem. 2014, 10, 1339–1346, doi:10.3762/bjoc.10.136

• copies of the luciferase and β-galactosidase genes under the control of the HIV-1 promoter [37][38][39][40]. Drugs, ester derivatives and GNPs were incubated with HIV-1 virus (NL4-3 strain) in triplicate for 30 min at 37 °C. The virus–drug mixture was added (1:1 by volume) to 10,000 TZM-bl cells per well