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

• hand, we finally accomplished the N-acylation reaction using n-BuLi in THF at −60 °C [15] in 60% yield. Removal of both protecting groups by catalytic hydrogenation, gave the desired compound 1 in 72% yield (Scheme 3). Compound 1 was subjected to a preliminary study to evaluate the antimicrobial

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• -acylation, wherein various homotyramine sulfonamides were treated with electrophile PIDA (15) in hexafluoroisopropanol to give the spirocyclic products 123 in high yields (Scheme 45). However, the similar spirocyclization could not successfully applied for the construction of six-membered spiropiperidine

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

Mechanochemistry of nucleosides, nucleotides and related materials

• Olga Eguaogie,
• Joseph S. Vyle,
• Patrick F. Conlon,
• Manuela A. Gîlea and
• Yipei Liang

Beilstein J. Org. Chem. 2018, 14, 955–970, doi:10.3762/bjoc.14.81

• nucleoside analogues with photoreactive materials. Thus, liquid-assisted grinding of the N-hydroxysuccinimidyl esters of o-, m- or p-phenylazobenzoic acids with excess D-threoninol or of the para isomer with an aminonucleoside in the presence of DMAP and ethyl acetate engendered chemoselective N-acylation

• -fluorouracil (5FU) and nucleoside analogue prodrugs subject to mechanochemical co-crystal or polymorph transformation. Nucleoside tritylation effected by hand grinding in a heated mortar and pestle. Persilylation of ribonucleoside hydroxy groups (and in situ acylation of cytidine) in a MBM. Nucleoside amine

• and carboxylic acid Boc protection using an improvised attritor-type mill. Nucleobase Boc protection via transient silylation using an improvised attritor-type mill. Chemoselective N-acylation of an aminonucleoside using LAG in a MBM. Azide–alkyne cycloaddition reactions performed in a copper vessel

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery

• Sabine Schuster,
• Beáta Biri-Kovács,
• Bálint Szeder,
• Viktor Farkas,
• László Buday,
• Zsuzsanna Szabó,
• Gábor Halmos and
• Gábor Mező

Beilstein J. Org. Chem. 2018, 14, 756–771, doi:10.3762/bjoc.14.64

• breast adenocarcinoma cancer cells (MCF-7) and on hormone independent human colon carcinoma cells (HT-29) were analyzed [22][25][27][28]. Thereby, it has been exposed, that an exchange of 4Ser by 4Lys followed by acylation of the ε-amino group with short chain fatty acids (SCFA) improved the cellular

Enzyme-free genetic copying of DNA and RNA sequences

• Marilyne Sosson and
• Clemens Richert

Beilstein J. Org. Chem. 2018, 14, 603–617, doi:10.3762/bjoc.14.47

• small heterocycles, such as pyridine, can increase the rate of the reaction [60]. Most probably, this effect was organocatalytic in nature, being caused by a pyridinium species that forms in the reaction medium, an effect known from the acceleration of DCC-induced acylation reactions with

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

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

• content of LPS comprises a complex mixture of structural homologs varying in the acylation pattern, the length of the (R)-3-hydroxyacyl- and (R)-3-acyloxyacyl long-chain residues and in the phosphorylation status of the β(1→6)-linked diglucosamine backbone. The structural heterogeneity of the lipid A

• lengths usually comprising 12–16 carbon atoms [16][17]. The endotoxic activity of lipid A depends on numerous factors such as acylation and phosphorylation pattern [18], the length of lipid chains, and the tertiary 3D structure of the MD-2 bound βGlcN(1→6)GlcN backbone [19][20]. The most profoundly

•  4B) [42][64]. Thus, lipid A directly participates in the formation of an active multimeric ligand–receptor complex, whereas the tightness and efficiency of dimerization strongly depends on specific structural characteristics such as the acylation pattern and the number of negative charges (e.g

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• synthesis of resonance-stabilized phosphorus ylides 81 (Scheme 51). The obtained ylides underwent further cyclization by the intramolecular acylation of the primary amino group to give the final bicyclic products 82 in 85–90% yields [67]. The synthesis of resonance-stabilized phosphorus ylides via the

A Brønsted base-promoted diastereoselective dimerization of azlactones

• Danielle L. J. Pinheiro,
• Gabriel M. F. Batista,
• Pedro P. de Castro,
• Leonã S. Flores,
• Gustavo F. S. Andrade and
• Giovanni W. Amarante

Beilstein J. Org. Chem. 2017, 13, 2663–2670, doi:10.3762/bjoc.13.264

• and Mannich acceptors [20][21][22][23]. Enolate anions derived from azlactone are effective intermediates for the functionalization of α-amino acids. However, the acylation of the enolate ion by another azlactone has been less reported in the literature [24][25][26]. This transformation affords an

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• the asymmetric synthesis of a monofluoroalkene using a chiral auxiliary (Scheme 13) [43]. The synthesis started with the alcohol protection of known compound 65 followed by chiral auxiliary removal and acylation of the resulting carboxylic acid. A HWE olefination was performed in two steps on 66 to

Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective

• Yaroslav D. Boyko,
• Valentin S. Dorokhov,
• Alexey Yu. Sukhorukov and
• Sema L. Ioffe

Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220

• -hydroxytryptophan derivative 79 using aminolysis and reduction with (CH3)3N·BH3 complex [47][49][69]. Acylation of 79 with pyruvoyl chloride gave amide 80, which was converted into dioxopiperazine 81 upon the action of trifluoroacetic acid. Subsequent water elimination furnished the title neoechinulin B analogue 77

Enzymatic separation of epimeric 4-C-hydroxymethylated furanosugars: Synthesis of bicyclic nucleosides

• Neha Rana,
• Manish Kumar,
• Vinod Khatri,
• Jyotirmoy Maity and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2017, 13, 2078–2086, doi:10.3762/bjoc.13.205

• hydroxy groups present in different sugars and sugar moieties of synthetic or naturally occurring glycosides, nucleosides, etc. Gotor et al. [11] have reported a lipase-mediated acylation of an equimolecular mixture of D/L-thymidine with acetonoxime levulinate as acylating agent and Pseudomonas cepacia

NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones

• Ken Takaki,
• Makoto Hino,
• Akira Ohno,
• Kimihiro Komeyama,
• Hiroto Yoshida and
• Hiroshi Fukuoka

Beilstein J. Org. Chem. 2017, 13, 1816–1822, doi:10.3762/bjoc.13.176

• -diketones and 1,2,3-triketones with enones and ynones have been investigated. The diketones gave α,β-double acylation products via unique Breslow intermediates isolable as acid salts, whereas the triketones formed stable adducts with the NHC instead of the coupling products. Keywords: Breslow intermediate

• = C(O)R1) reacted with enones III in the presence of thiazolium carbene catalysts to give double acylation products IV in good yields [15]. If enones can be replaced by ynones III in the reaction with benzils, alkenes IV having three acyl moieties would be formed directly. Related products were

• recently obtained by the dimsyl anion-promoted double acylation of enones with benzils, followed by dehydrogenation of the resulting alkanes in one pot [16]. Moreover, if the reaction of cyclic 1,2-diketone I (G = C(O)R1) with activated alkenes may take place similarly, this reaction could be utilized as a

Mechanochemical enzymatic resolution of N-benzylated-β³-amino esters

• Mario Pérez-Venegas,
• Gloria Reyes-Rangel,
• Adrián Neri,
• Jaime Escalante and
• Eusebio Juaristi

Beilstein J. Org. Chem. 2017, 13, 1728–1734, doi:10.3762/bjoc.13.167

• applications on a large scale [45][46]. Very recently, Hernández, Frings, and Bolm developed a method to carry out the kinetic resolution of secondary alcohols through selective acylation using Candida antarctica lipase B, under solvent-free ball-milling conditions [47][48]. Inspired by this ground-breaking

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

A novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• -substituted isoquinolines at C-1, followed by reaction with iodine. Subsequent Suzuki cross-coupling of the resulting 1-iodoisoquinolines to methyl 2-(isoquinolin-1-yl)benzoates and intramolecular acylation of the corresponding carboxylic acids with Eaton’s reagent afforded five alkaloids of the

• starting from an isoquinoline bearing an ester group at C-8. In a photoredox-catalyzed direct C–H arylation a 4-methoxyphenyl residue from a methoxyphenyldiazonium salt was introduced at C-1, and after ester hydrolysis intramolecular Friedel–Crafts acylation afforded menisporphine (2). In continuation of

• acylation following Kunitomo’s strategy. Main advantage of this approach should be that the laborious introduction of the carboxy residue at a late stage of the total synthesis is circumvented. Alternatively, quenching of the 1-magnesiated alkoxyisoquinolines with iodine should lead to 1-iodoisoquinolines

Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine

• Jimena E. Díaz,
• Silvia Ranieri,
• Nadia Gruber and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2017, 13, 1470–1477, doi:10.3762/bjoc.13.145

• required functionalization of both amino groups present in 2-ABA was achieved by different routes involving selective N-acylation and cesium carbonate-mediated N-alkylation reactions, avoiding protection/deprotection steps. The heterocycles were efficiently synthesized in short reaction times by microwave

• , the selective acylation of the aliphatic amino group was achieved by the treatment of the diamine with benzoic acid in the presence of Zr(azobenzene-4,4´-dicarboxylate) [43], with tert-butylperoxybenzoate [44] and with isopropenyl acetate [45], or by a DCC-mediated coupling with a carboxylic acid [38

• amides 4a–c employing a THF solution of borane (yields 82–93%; see Supporting Information File 1 and Scheme 2). The synthesis of N-(2-aminobenzyl)amides 4a–k was achieved by selective N-acylation of 2-ABA or its N-substituted derivatives 3a–c, whose preparation is depicted in Scheme 2. In spite of the

A new member of the fusaricidin family – structure elucidation and synthesis of fusaricidin E

• Marcel Reimann,
• Louis P. Sandjo,
• Luis Antelo,
• Eckhard Thines,
• Isabella Siepe and
• Till Opatz

Beilstein J. Org. Chem. 2017, 13, 1430–1438, doi:10.3762/bjoc.13.140

• the esterification with DIC/DMAP [12] as the double acylation product 18 could be detected (Scheme 3). Further investigations suggested DMAP to be responsible for the cleavage of the ΨMe,Me'Pro and after reduction of the amount of DMAP to 5 mol %, nearly no doubly acylated product was found. Besides

• single signal set, so the fate of the assumed minor stereoisomer remains unclear and it was probably lost during HPLC purification. The analysis also revealed that the acylation with the GHPD side chain was selective for the amine and no O-acylated product was formed. Side chain protecting groups were

A speedy route to sterically encumbered, benzene-fused derivatives of privileged, naturally occurring hexahydropyrrolo[1,2-b]isoquinoline

• Olga Bakulina,
• Alexander Ivanov,
• Vitalii Suslonov,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2017, 13, 1413–1424, doi:10.3762/bjoc.13.138

• ) N-acylation of the imine component followed by intramolecular Mannich reaction or (b) Mannich-type addition of the HPA enolate to a protonated imine component followed by intramolecular aminolysis of the cyclic anhydride moiety in Mannich adduct 13 (Scheme 3) [1]. Investigation of the CCR leading to

Nitration of 5,11-dihydroindolo[3,2-b]carbazoles and synthetic applications of their nitro-substituted derivatives

• Roman A. Irgashev,
• Nikita A. Kazin,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2017, 13, 1396–1406, doi:10.3762/bjoc.13.136

• chemical methods for modification of ICZ derivatives. We have recently reported several synthetic procedures for regioselective C2,8-formylation and acylation of indolo[3,2-b]carbazoles, bearing electron-rich aromatic or heteroaromatic substituents at C-6 and C-12, and also demonstrated the usage of the

An improved preparation of phorbol from croton oil

• Alberto Pagani,
• Simone Gaeta,
• Andrei I. Savchenko,
• Craig M. Williams and
• Giovanni Appendino

Beilstein J. Org. Chem. 2017, 13, 1361–1367, doi:10.3762/bjoc.13.133

• , since the irritancy of phorbol esters is critically dependent on their acylation profile [6]. However, the native phorboid profile of croton oil is still poorly characterized in terms of analytical profile [24], and the recovery of the native highly lipophilic phorboid esters from the lipid matrix of

BODIPY-based fluorescent liposomes with sesquiterpene lactone trilobolide

• Ludmila Škorpilová,
• Silvie Rimpelová,
• Michal Jurášek,
• Miloš Buděšínský,
• Jana Lokajová,
• Roman Effenberg,
• Petr Slepička,
• Tomáš Ruml,
• Eva Kmoníčková,
• Pavel B. Drašar and
• Zdeněk Wimmer

Beilstein J. Org. Chem. 2017, 13, 1316–1324, doi:10.3762/bjoc.13.128

• reaction of 4-iodo-L-phenylalanine with thionyl chloride in MeOH in quantitative yield [33]. The successive acylation of the α-amino group with 5-azidovaleric acid catalyzed by T3P (propylphosphonic anhydride) in the mixture of pyridine and AcOEt gave azidoterminated product 1 in 70% yield. Alkaline

Total synthesis of elansolids B1 and B2

• Liang-Liang Wang and
• Andreas Kirschning

Beilstein J. Org. Chem. 2017, 13, 1280–1287, doi:10.3762/bjoc.13.124

• iodide 17 after O-acylation, iodination of the terminal alkyne and finally diimide-mediated syn-reduction [11]. Next, DDQ-mediated removal of the PMB protecting group yielded vinyl iodide 18. The synthesis of both fragments 13 and 18 set the stage for the Suzuki–Miyaura coupling which delivered the

Glycoscience@Synchrotron: Synchrotron radiation applied to structural glycoscience

• Serge Pérez and
• Daniele de Sanctis

Beilstein J. Org. Chem. 2017, 13, 1145–1167, doi:10.3762/bjoc.13.114

• oligosaccharide acceptor and GDP lead to the understanding of the FUT1 mechanism [40]. Carbohydrate esterases: Carbohydrate esterases perform the de-O or de-N-acylation of carbohydrates. From a mechanistic point of view, this family of enzymes is divided into two classes, according to the dual role played by the

α-Acetoxyarone synthesis via iodine-catalyzed and tert-butyl hydroperoxide-mediateded self-intermolecular oxidative coupling of aryl ketones

• Liquan Tan,
• Cui Chen and
• Weibing Liu

Beilstein J. Org. Chem. 2017, 13, 1079–1084, doi:10.3762/bjoc.13.107

• previous reports [22][29]. Conclusion In summary, we have developed an efficient, novel, and metal-free synthesis of α-acetoxyaryl ketones from aryl ketones using I2−TBHP. A facile α-acylation reaction involving self-intermolecular oxidative coupling of aryl ketones was observed for the first time in the