Progress in metathesis chemistry

• Karol Grela and
• Anna Kajetanowicz

Beilstein J. Org. Chem. 2019, 15, 2765–2766, doi:10.3762/bjoc.15.267

• catalysts work and decompose, how macrocycles are formed in ring-closing metathesis, etc. Representative examples of these directions have been the subject of the current, third thematic issue on Olefin Metathesis, including highly educative reviews on tandem olefin metathesis–Suzuki–Miyaura cross coupling

AgNTf₂-catalyzed formal [3 + 2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives

• Ziping Cao,
• Jiekun Zhu,
• Li Liu,
• Yuanling Pang,
• Laijin Tian,
• Xuejun Sun and
• Xin Meng

Beilstein J. Org. Chem. 2019, 15, 2623–2630, doi:10.3762/bjoc.15.255

• tethered to cyclohexadienones that can be converted into complex polycycles by Ag-carbenoid-initiated cascades [16]. Recently, Zhu’s group developed a tandem 1,3‑dipolar cycloaddition/cyclopropanation silver-catalyzed reaction of enynals with alkenes [17]. In our previous studies, this silver carbene

Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis

• Zhen Cao,
• Aline Lacoudre,
• Cybille Rossy and
• Brigitte Bibal

Beilstein J. Org. Chem. 2019, 15, 2465–2472, doi:10.3762/bjoc.15.239

• of the two L2·(AgOTf)2 stereoisomers highlighted their different geometry. The catalytic activity of all silver(I) complexes was effective under homogeneous conditions in two tandem addition/cycloisomerization of alkynes using 0.5–1 mol % of catalytic loading. Keywords: coordination macrocycle

• candidates for directional metal coordination. Herein, a new syn-atropisomer of 9,10-DPA ortho-substituted by two thioethers is exploited as a ligand for silver(I) salts. The impact of this bis-thioether ligand on silver(I) homogeneous catalysis is evaluated in two tandem addition/cycloisomerization

• complexes 1a–d were evaluated as homogeneous catalysts in two tandem addition/cycloisomerization reactions using alkynes 2 and 3. 2-Alkynylbenzaldehyde 2 [58][59] was chosen as the first model substrate for a cyclization reaction in the presence of methanol as a second nucleophile. This tandem addition

Functionalization of 4-bromobenzo[c][2,7]naphthyridine via regioselective direct ring metalation. A novel approach to analogues of pyridoacridine alkaloids

• Benedikt C. Melzer,
• Alois Plodek and
• Franz Bracher

Beilstein J. Org. Chem. 2019, 15, 2304–2310, doi:10.3762/bjoc.15.222

• -catalysed intramolecular tandem stannylation/biaryl coupling protocol gave the attempted pentacyclic products [32]. However, having the biaryls 20a and 20b prepared we intended to develop a new approach to pyrido[4,3,2-mn]acridines by an alternative intramolecular cyclization step. To reach that aim, the

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

Synthesis of benzo[d]imidazo[2,1-b]benzoselenoazoles: Cs₂CO₃-mediated cyclization of 1-(2-bromoaryl)benzimidazoles with selenium

• Mio Matsumura,
• Yuki Kitamura,
• Arisa Yamauchi,
• Yoshitaka Kanazawa,
• Yuki Murata,
• Tadashi Hyodo,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2019, 15, 2029–2035, doi:10.3762/bjoc.15.199

• Ar(aryl)–Se bonds [9][10][11][12][13]. Various metals, such as Pd, Ni, Fe, and Cu have been used to catalyze the reactions of a Se source with aryl donors. Among these, Cu-catalyzed tandem cyclization via a one-step Ullmann-type Se-arylation and Csp2–H selenation are efficient methods for

• group having bromine to generate the tetracyclic target molecule. Conclusion Benzo[d]imidazo[2,1-b]benzoselenoazoles were prepared via Cs2CO3-mediated tandem cyclization followed by reaction of 1-(2-bromoaryl)benzimidazoles with Se powder without a transition metal catalyst. The molecular structure of

Synthesis of a [6]rotaxane with singly threaded γ-cyclodextrins as a single stereoisomer

• Jason Yin Hei Man and
• Ho Yu Au-Yeung

Beilstein J. Org. Chem. 2019, 15, 1829–1837, doi:10.3762/bjoc.15.177

• chromatographic time scale. The [n]rotaxanes were all purified by preparative HPLC and characterized by 1H NMR, 13C{1H} NMR, HRESIMS, and tandem MS. The HRESIMS spectra of 3R, 4R, 5R and 6R all show an isotopic pattern that is consistent with the respective molecular formula (Figures S20–S23 in Supporting

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• trace of final product, whereas the reaction was not completed with (E)-but-2-enal (entry 17 and 18, Table 1). Wang et al. have developed a Cu(II)-catalyzed tandem reaction between ketonic pyridine 90 and benzylamine 91 using DMF as a solvent at 110 °C, in the presence of oxygen as a clean oxidant

• which underwent resonance to give 94. This was followed by intramolecular amination, oxidative dehydrogenation, and rearrangement to yield the final product 37 (Scheme 31). A one-pot, tandem reaction promoted by a I2/CuO system to synthesize imidazo[1,2-a]pyridines was reported by Cai et al. (Scheme 32

• tandem synthesis of 3-iodoimidazo[1,2-a]pyridines (Scheme 35) [120]. The synthesis was similar to that reported by Kumar and co-workers with the difference of a heterogeneous catalytic system and iodination of the product [121]. Molecular iodine was used as an iodinating agent in the reaction. In this

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• observable signal. Subsequent to IDA, Nau and co-workers conceptualized a novel approach towards enzyme assays, termed supramolecular tandem assay (STA) (Scheme 1b) [5]. STA is envisaged as a time-resolved version of IDA and the key idea is that the competitor is not added, but rather created during the

Alkylation of lithiated dimethyl tartrate acetonide with unactivated alkyl halides and application to an asymmetric synthesis of the 2,8-dioxabicyclo[3.2.1]octane core of squalestatins/zaragozic acids

• Herman O. Sintim,
• Hamad H. Al Mamari,
• Hasanain A. A. Almohseni,
• Younes Fegheh-Hassanpour and
• David M. Hodgson

Beilstein J. Org. Chem. 2019, 15, 1194–1202, doi:10.3762/bjoc.15.116

• area have recently culminated in two communicated syntheses of 6,7-dideoxysqualestatin H5 (DDSQ (2), Figure 1) [12][13]. The centrepiece of both of these strategies is a rhodium(II)-catalysed tandem carbon ylide formation from a diazoketone 3 (Scheme 1) and stereoselective [3 + 2] cycloaddition with a

Unexpected polymorphism during a catalyzed mechanochemical Knoevenagel condensation

• Sebastian Haferkamp,
• Andrea Paul,
• Adam A. L. Michalchuk and
• Franziska Emmerling

Beilstein J. Org. Chem. 2019, 15, 1141–1148, doi:10.3762/bjoc.15.110

• situ and in real-time by tandem synchrotron powder X-ray diffraction and Raman spectroscopy. For synthesis of p-fluorobenzylidene malonodinitrile (3a) the reaction product crystallizes according to two different pathways, depending on the concentration of base catalyst. At high concentrations of

Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• structure. Those starting materials must be added all together in the reaction container and, therefore, other approaches [67][68][69] featuring sequential (domino, tandem or cascade) [70][71] reactions, where one intermediate is initially preformed before additional reagents are added, are not included in

• metal catalyst. Through a tandem three-component cross-dehydrogenative coupling (CDC), they prepared, in a single step, more than thirty isoindolinone derivatives 4, including those originated from sulfonamides and carboxamides (Scheme 1). The scope of the reaction includes aromatic, some aliphatic and

Halogen bonding and host–guest chemistry between N-alkylammonium resorcinarene halides, diiodoperfluorobutane and neutral guests

• Fangfang Pan,
• Mohadeseh Dashti,
• Michael R. Reynolds,
• Kari Rissanen,
• John F. Trant and
• Ngong Kodiah Beyeh

Beilstein J. Org. Chem. 2019, 15, 947–954, doi:10.3762/bjoc.15.91

• are working in tandem and concertedly to form networks of non-covalent interactions stabilizing the dimeric and capsular structures in the solid state. The inclusion guests affect the geometry of the cavity of the hex-NARBr and cy-NARCl, thus affecting the halogen bonding connection in the final

Synthesis of (macro)heterocycles by consecutive/repetitive isocyanide-based multicomponent reactions

• Angélica de Fátima S. Barreto and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2019, 15, 906–930, doi:10.3762/bjoc.15.88

• reactions such as those represented in Scheme 8 were also reported in the same work. Al-Tel et al. described the tandem combination of Groebke–Blackburn–Bienaymé and Ugi or Passerini reactions in the same reaction flask without isolating any intermediate, allowing the preparation of complex heterocycles

• involving a tandem combination of Groebke–Blackburn–Bienaymé and Ugi reaction for the synthesis of a complex heterocycle [26]. 5CR involving a tandem combination of Groebke–Blackburn–Bienaymé and Passerini reaction for the synthesis of a complex heterocycle [26]. Synthesis of tubugis via three consecutive

Solid-phase synthesis of biaryl bicyclic peptides containing a 3-aryltyrosine or a 4-arylphenylalanine moiety

• Iteng Ng-Choi,
• Àngel Oliveras,
• Lidia Feliu and
• Marta Planas

Beilstein J. Org. Chem. 2019, 15, 761–768, doi:10.3762/bjoc.15.72

• mixture was analyzed by HPLC and characterized by mass spectrometry. The latter revealed the formation of the expected biaryl bicyclic peptide 1 together with a less intense signal at [M − 18 + H]+, which was attributed to peptide fragmentation during the analysis, as confirmed by tandem mass spectrometry

• group removal, macrolactamization and final cleavage yielded the biaryl bicyclic peptide 3. Mass spectra showed a signal at [M + H]+ together with a major one at [M − 18 + H]+ attributed to the fragmentation of 3 during the analysis, as confirmed by tandem mass spectrometry. Conclusion A methodology for

Synthesis of 2H-furo[2,3-c]pyrazole ring systems through silver(I) ion-mediated ring-closure reaction

• Vaida Milišiūnaitė,
• Rūta Paulavičiūtė,
• Eglė Arbačiauskienė,
• Vytas Martynaitis,
• Wolfgang Holzer and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2019, 15, 679–684, doi:10.3762/bjoc.15.62

• derivatives [15][16][17][18]. For example, Damera et al. reported an efficient synthesis of 2-substituted benzo[b]furans with good yields by the base-promoted cyclization of easily accessible 2-alkynylphenols [19]. Recently, 2-arylbenzo[b]furans were conveniently synthesized by the one-pot tandem Hiyama

Intramolecular cascade annulation triggered by rhodium(III)-catalyzed sequential C(sp²)–H activation and C(sp³)–H amination

• Liangliang Song,
• Guilong Tian,
• Johan Van der Eycken and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2019, 15, 571–576, doi:10.3762/bjoc.15.52

• intramolecular migratory insertion affords intermediate C. Reductive elimination and subsequent oxidative addition give intermediate D. Then two pathways are involved in the following steps. In the main pathway (path a), intermediate D undergoes β-H elimination and tandem cyclization to give product 3a and Rh–H

A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• reaction [20], tandem approach from (S)-Wynberg lactone [21], chiral ruthenium-catalyzed N-demethylative rearrangement of 1,2-isoxazolidines [22], gold(I)-catalyzed cyclization of a propargylic N-hydroxylamine [23], from β-sulfinamido ketones derived from chiral sulfinimines [24], and a Kornblum–DeLaMare

Aqueous olefin metathesis: recent developments and applications

• Valerio Sabatino and
• Thomas R. Ward

Beilstein J. Org. Chem. 2019, 15, 445–468, doi:10.3762/bjoc.15.39

• olefin-bearing biotin 84 was selected as olefinic partner for the CM reaction with the modified antibody, yielding IgG-Fc-Ahc32-biotin (Scheme 19b). The conjugated protein can be selectively pulled-down with avidin beads and analyzed by tandem MS after tryptic digestion. This strategy suggests that CM

Tandem copper and photoredox catalysis in photocatalytic alkene difunctionalization reactions

• Nicholas L. Reed,
• Madeline I. Herman,
• Vladimir P. Miltchev and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2019, 15, 351–356, doi:10.3762/bjoc.15.30

• describe a method for alkene oxyamination and diamination that utilizes simple carbamate and urea groups as nucleophilic heteroatom donors. This method uses a tandem copper–photoredox catalyst system that is operationally convenient. The identity of the terminal oxidant is critical in these studies. Ag(I

• ) complex. We describe herein the results of this investigation, which has led to the identification of a tandem photoredox copper(II) catalytic system for the net-oxidative difunctionalization of alkenes. Results and Discussion A range of mild oxidants can oxidize copper(I) to copper(II), and the use of

Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• cyclization under transition-metal free conditions. With the addition of a radical scavenger such as TEMPO or BHT, the reaction was suppressed remarkably. In the same year, Dai’s group also reported the ring-opening-initiated tandem cyclization of cyclopropanols 91 with acrylamides 122 or 2-isocyanobiphenyls

• ring-opening and chlorination of cyclopropanols with aldehydes. Ag(I)-catalyzed ring-opening/alkynylation of cyclopropanols with EBX. Na2S2O8-promoted ring-opening/alkylation of cyclopropanols with acrylamides. Cyclopropanol ring-opening initiated tandem cyclization with acrylamides or 2

Mechanistic studies of an L-proline-catalyzed pyridazine formation involving a Diels–Alder reaction with inverse electron demand

• Anne Schnell,
• J. Alexander Willms,
• S. Nozinovic and
• Marianne Engeser

Beilstein J. Org. Chem. 2019, 15, 30–43, doi:10.3762/bjoc.15.3

• components [5][6]. As a drawback of MS, isomers typically are hard to analyze as they have the same mass and thus lead to the same signal. However, they can be distinguished in fortunate cases by more sophisticated approaches like tandem mass spectrometry [3], ion mobility mass spectrometry [21], or coupling

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• substituent (Figure 15) at the nitrogen atoms were investigated by Copéret and Thieuleux et al. in the tandem ring-opening–ring-closing alkene metathesis (RO–RCM) of cis-cyclooctene (47) and their performance were compared to those of the classical GII-SIMes and GII-IMes [29]. The dissymmetry of the NHC

Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

• Christiane Schultze and
• Bernd Schmidt

Beilstein J. Org. Chem. 2018, 14, 2991–2998, doi:10.3762/bjoc.14.278

• Christiane Schultze Bernd Schmidt Universität Potsdam, Institut fuer Chemie, Karl-Liebknecht-Straße 24–25, D-14476 Potsdam-Golm, Germany 10.3762/bjoc.14.278 Abstract 8-Allylcoumarins are conveniently accessible through a microwave-promoted tandem Claisen rearrangement/Wittig olefination

• defined order. One class of products, pyrano[2,3-f]chromene-2,8-diones, were inaccessible through direct RCM of an acrylate, but became available from the analogous allyl ether via an assisted tandem catalytic RCM/allylic oxidation sequence. Keywords: coumarins; heterocycles; isomerization; olefin

• application of sequential one-pot transformations and motivated by the relevance of prenylated and other substituted coumarins in natural products and medicinal chemistry, we [27][28][29] and others [30] have investigated a microwave-promoted tandem reaction for the synthesis of 8-substituted coumarins over

Copper(I)-catalyzed tandem reaction: synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and alkynes

• Muhammad Israr,
• Changqing Ye,
• Munira Taj Muhammad,
• Yajun Li and
• Hongli Bao

Beilstein J. Org. Chem. 2018, 14, 2916–2922, doi:10.3762/bjoc.14.270