2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• properties. Herein, starting from readily available anthranilic acid, an efficient synthesis of 2,4-bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridine derivatives was accomplished via a one-pot double Sonogashira cross-coupling method. The UV-visible absorption and emission properties of the synthesized

• catalysis. With this precursor in hand, we intended to expand the π-conjugation by introducing two arylethynyl groups by Sonogashira reactions [66][67][68][69]. For the optimization, we studied the reaction of 2 with phenylacetylene (3a) and we obtained the desired product 4a in up to 72% as best yield

• of the temperature. We found that increasing the temperature to 90 or 100 °C did not lead to any improvement (Table 1, entries 6 and 7). The best result for the Sonogashira coupling reaction between intermediate 2 and phenylacetylene (3a) was obtained using 0.6 mol % of Pd(PPh3)4, 1.2 mol % of CuI in

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

• Pezhman Shiri,
• Ali Mohammad Amani and
• Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

• 134 were used as starting material in the Sonogashira and Suzuki reactions. The Sonogashira−Hagihara cross-coupling led to alkynylation at position 5 of the triazole ring in the presence of CuI and Pd(PPh3)4 as catalytic system as well as K3PO4 as base in THF as solvent at 65 °C. However, the Suzuki

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• ) and 5′-O-DMTr-protected N4-(dimethylaminomethylene)-2′-deoxycytidine (134a–d) by using Sonogashira cross coupling reaction between the propargylated nucleobases, i.e., 1-propargylthymine, N4-acetyl-1-propargylcytosine, N6-benzoyl-9-propargyladenine, and N2-isobutyryl-9-propargylguanine (13a–d) and 5

• -dimethoxytrityl-5-(4-(thymin-1-yl)phenyl)ethynyl-2′-deoxyuridine (141) were synthesized via a Sonogashira cross coupling reaction between the N1-(3/4-iodophenyl)thymine derivatives 136c and 136d and 2′-deoxy-5-ethynyluridine derivative 139 (Scheme 35) [75]. All four nucleoside monomers were converted into

• ′-deoxypyrrolocytidine (146) which has adenine attached to the 6-position of the pyrrolo-2′-deoxycytidine through a methylene linker. The double-headed nucleoside 146 was synthesized through the Sonogashira coupling reaction between 5′-O-DMTr-5-iodo-2′-deoxyuridine (144) and N9-propargyladenine (45) followed by

Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes

• Tsutomu Kimura,
• Koto Sekiguchi,
• Akane Ando and
• Aki Imafuji

Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94

• Sonogashira coupling reaction with organic halides. The dehydrohalogenation of gem-dihaloalkanes, vic-dihaloalkanes, and haloalkenes with strong bases is often used for the synthesis of alkynes [2]. An alternative strategy for the synthesis of alkynes is the conversion of carbonyl compounds through one-carbon

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

• Joseane A. Mendes,
• Paulo R. R. Costa,
• Miguel Yus,
• Francisco Foubelo and
• Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

• Hale and Hatakeyama [57]. Recently, Burton’s group developed some efficient and tin-free total syntheses of all three inthomycins A–C ((+)-1, (+)-2, and (−)-3) using a Suzuki or Sonogashira cross-coupling of the (E)- or (Z)-alkenyl iodides 130 with the dienylboronic ester 128 as key step (Schemes 18–22

• be poor (<40%). Therefore, enyne 127 was selected as a coupling partner for the key Sonogashira reaction of alkenyl iodide (Z)-(+)-130a to construct the required (Z,Z,E)-triene for completion of the inthomycin A ((+)-1) synthesis. Fortunately, the alkenyl iodide (Z)-(+)-130a coupled smoothly with

• functional groups and isomerizable double bonds in the conjugated triene moiety. Various stereoselective cross-coupling reactions such as Stille, Suzuki, or Sonogashira or Suzuki–Miyaura have been utilized to construct the geometrically distinctive polyene systems of inthomycins A–C (1–3). The elegant work

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• helicenes with interesting electronic properties. Results and Discussion Synthesis In accordance with the above strategy, we first synthesized ortho-halogen alkynylazines 1a,b via the Sonogashira reaction of commercially available 2,3-dichloroquinoxaline and 2,3-dichloropyrazine with phenylacetylene using a

• catalytic systems Pd(PPh3)4/K3PO4/THF (method A) and Pd(PPh3)4/K3PO4/1,4-dioxane (method B) were less effective. 3-Alkynyl-2-carbazolylazines can also be prepared using an alternative synthetic sequence, i.e., the Suzuki–Miyaura arylation–Sonogashira reaction. It should be noted that in the case of 2,3

• /H2O catalytic system gave a mixture of the corresponding mono- and dicarbazolyl derivatives 4b (80%) and 5b (8%). The products were easily separated by column chromatography. 3-Bromo-2-carbazolylpyridine 4b was then introduced into the Sonogashira reaction with phenylacetylene giving rise to 3-alkynyl

Pentannulation of N-heterocycles by a tandem gold-catalyzed [3,3]-rearrangement/Nazarov reaction of propargyl ester derivatives: a computational study on the crucial role of the nitrogen atom

• Giovanna Zanella,
• Martina Petrović,
• Dina Scarpi,
• Ernesto G. Occhiato and
• Enrique Gómez-Bengoa

Beilstein J. Org. Chem. 2020, 16, 3059–3068, doi:10.3762/bjoc.16.255

• mixture with unknown products. Then, the iodoenesulfonamide 12 was coupled with (±)-butyn-3-ol under Sonogashira conditions [52] to afford the enynyl alcohol 13, which was treated with acetic anhydride to provide the enynyl acetate 14 in a yield of 67% over two steps. Then, we applied the typical

• was prepared via the palladium-catalyzed reduction of the corresponding phosphate 17 [54]. Iodination and Sonogashira coupling, followed by acetylation led to the formation of the desired enynyl acetate 20. This compound was treated with 5 mol % Ph3PAuCl/AgSbF6 in DCM, and after 6 h, this afforded the

Changed reactivity of secondary hydroxy groups in C8-modified adenosine – lessons learned from silylation

• Jennifer Frommer and
• Sabine Müller

Beilstein J. Org. Chem. 2020, 16, 2854–2861, doi:10.3762/bjoc.16.234

• being preferentially formed. Optimization of the protection scheme lead to a new and economic route to the desired C8-alkynylated building block and its incorporation in RNA. Keywords: nucleoside chemistry; protecting groups; RNA synthesis; Sonogashira reaction; Introduction Oligoribonucleotides

• phosphoramidite building block 9 (Scheme 2). Results and Discussion Typically, the synthesis of C8-alkynyl derivatives relies on C8-bromoadenosine as reactant for the Sonogashira cross-coupling reaction to introduce the amino linker N-(propyn-2-yl)-6-(trifluoroacetamido)hexanamide (L) bearing an alkynyl moiety

• [25]. Therefore, we decided to start the synthesis with the preparation of the C8-brominated derivative. Halogenation with bromine was achieved in good yields, however, the following Sonogashira reaction reproducibly proceeded with very low yields (data not shown). Therefore, we changed the used

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• connected asymmetric bowls, as well as atropisomerism, was constructed by Hirao and his two group members, namely Amaya and Kobayashi, starting from the same bromo derivative 82. First it was converted into ethynylsumanene 91 using a Sonogashira-coupling which on subsequent desilylation and Glaser-coupling

• subsequently transformed into the trimethylsilylethynyl derivatives 147 and 148 by employing the Sonogashira coupling reaction. Next, compounds 147 and 148 were reacted with HCl in CH3COOH to provide the tris(chlorovinyl) derivatives 149 and 150 which were then subjected to flash vacuum pyrolysis to afford the

Efficient [(NHC)Au(NTf₂)]-catalyzed hydrohydrazidation of terminal and internal alkynes

• Maximillian Heidrich and
• Herbert Plenio

Beilstein J. Org. Chem. 2020, 16, 2080–2086, doi:10.3762/bjoc.16.175

• even when using aryl-, alkylacetylenes, or electronically different aryl groups in tolanes. However, the steric bulk of a single methyl group in 2-methyltolane led to the selective formation of the single addition product 7h, but even such sterically hindered tolanes (synthesized via Sonogashira

Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines

• Ksenia I. Kaskevich,
• Anastasia A. Babushkina,
• Vladislav V. Gurzhiy,
• Dmitrij M. Egorov,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2020, 16, 1947–1954, doi:10.3762/bjoc.16.161

• thiazolopyrimidine-5-ones by reacting 6-methyl-2-thiouracils with bromoethynylketones has been reported by Shishkin and co-workers (Scheme 4) [20]. The authors for the first time proved the structure of the 5-oxo isomer by single crystal X-ray diffraction analysis. The Pd-catalyzed Sonogashira coupling reaction

• ]thiazol-2-yl)-2-(7-R-5-oxo-5H-thiazolo[3,2-a]pyrimidin-3-yl)acetonitriles. Synthesis of 3-acyl-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-ones. Sonogashira coupling reaction of 6-amino-2-thiouracil with propargyl bromide. Reactions of 6-substituted 2-thiouracils 1a,b with chloroethynylphosphonates 2a–c

Regiodivergent synthesis of functionalized pyrimidines and imidazoles through phenacyl azides in deep eutectic solvents

• Paola Vitale,
• Luciana Cicco,
• Ilaria Cellamare,
• Filippo M. Perna,
• Antonio Salomone and
• Vito Capriati

Beilstein J. Org. Chem. 2020, 16, 1915–1923, doi:10.3762/bjoc.16.158

• ], (c) carbon–sulfur bond-forming reactions [9], (d) directed ortho-metalation and nucleophilic acyl substitution strategies [10], (e) Pd-catalyzed aminocarbonylation of aryl iodides, Suzuki–Miyaura and Sonogashira cross-coupling reactions [11][12][13], (f) Cu-catalyzed C–N coupling reactions [14], and

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

• Lucas Guillemard and
• Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

• of the independently formed intermediate furnished the expected coupling products under generally mild reaction conditions. Furthermore, a merge of metal-catalyzed C–H functionalization and photocatalysis was also astutely employed to design modern versions of Sonogashira-type reactions as well as

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• investigated for its use as a rigid isolating unit in the synthesis of multichromophoric arrays. Sonogashira cross-coupling conditions are utilized to attach various porphyrins and boron dipyrromethenes (BODIPYs) to the triptycene scaffold. While there are previous examples of triptycene porphyrin complexes

• evident linearity in these systems. Moreover, initial UV–vis and fluorescence studies show the promise of triptycene as a linker for electron transfer studies, showcasing its isolating nature. Keywords: BODIPY; Pd-catalyzed cross-coupling; porphyrins; Sonogashira cross-coupling; triptycene; Introduction

• complexes such as 2 were synthesized by us with the purpose of conducting electron transfer studies [25]. Both Suzuki and Sonogashira cross-coupling reactions were employed to realize this new class of triptycene-linked trimeric porphyrins. The three porphyrins, or three BODIPYs in 2 were either linked

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• Glaser-coupling reactions [37]. Conventionally, an alkynylation of the BODIPY core has been achieved by palladium-catalyzed Sonogashira cross-coupling with halogenated BODIPYs (Figure 1b) [35][37]. However, due to the coexistence of multiple C–H bonds, a regioselective direct C–H alkynylation of the

• novel functional fluorescent materials. (a) Chemical structures of BODIPY (1) and dipyrromethane (2). (b) C–C bond forming alkynylations of pyrrole and its derivatives by Sonogashira coupling and electrophilic alkynylation. (c) Peripheral alkynylated BODIPY derivatives (3–6) prepared in this work. TIPS

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• employed in diverse organic reactions, including Suzuki reactions [64], Sonogashira reactions [65], transesterifications of triglycerides [66], hydrogenation reactions [67], N-heterocycle syntheses [68], cleavage of propargyl phenol ethers [69], etc. [70][71][72][73][74][75]. In this review article, we

• multitask nanocatalyst was used for one-pot Sonogashira-“click”/“click”-Heck sequences [87]. Palladium(II) acetate, copper(II) acetate, and charcoal were dispersed in methanol. In order to remove oxygen from the reaction mixture, hydrogen gas was passed through the medium. Then, the solution was stirred at

• ambient temperature for 12 h under a hydrogen atmosphere. Finally, the Pd–Cu/C catalyst was collected by filtration, washed with methanol, and dried. An efficient one-pot sequential Sonogashira-“click” reaction toward heterocyclic structures was disclosed using the same catalyst. In this regard

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• π-extension through a Suzuki–Miyaura coupling, Sonogashira coupling, and electrophilic alkyne carbocyclization [18]. Given the successful synthesis of the angularly fused phosphahelicenes, we became interested in the further exploitation of 7-hydroxybenzo[b]phosphole as an intermediate for the

Controlling alkyne reactivity by means of a copper-catalyzed radical reaction system for the synthesis of functionalized quaternary carbons

• Goki Hirata,
• Yu Yamane,
• Naoya Tsubaki,
• Reina Hara and
• Takashi Nishikata

Beilstein J. Org. Chem. 2020, 16, 502–508, doi:10.3762/bjoc.16.45

• reaction of 3 equivalents of terminal alkyne 1 (aryl substituted alkyne) and an α-bromocarbonyl compound 2 (tertiary alkyl radical precursor) undergoes tandem alkyl radical addition/Sonogashira coupling to produce 1,3-enyne compound 3 possessing a quaternary carbon in the presence of a copper catalyst

• ; Introduction Terminal alkynes are undoubtedly useful functional groups for organic synthesis, and they can undergo a variety of reactions [1]. The C–C triple bond of an alkyne is suitable for addition reactions, whereas the terminal hydrogen atom is a good target for cross-coupling by using Sonogashira and

• alkyl radicals generated from the reaction of a copper catalyst and an α-bromocarbonyl compound can undergo i) Sonogashira type couplings via an alkynyl-Cu intermediate [20], ii) cis-hydro tertiary alkylations via 1-alkenyl-Cu [21], and iii) trans-hydro tertiary alkylations via atom-transfer radical

Palladium-catalyzed Sonogashira coupling reactions in γ-valerolactone-based ionic liquids

• László Orha,
• József M. Tukacs,
• László Kollár and
• László T. Mika

Beilstein J. Org. Chem. 2019, 15, 2907–2913, doi:10.3762/bjoc.15.284

• -ethoxyvalerate as a partially bio-based solvent can be utilized as alternative reaction medium for copper- and auxiliary base-free Pd-catalyzed Sonogashira coupling reactions of aryl iodides and functionalized acetylenes under mild conditions. Twenty-two cross-coupling products were isolated with good to

• wide applicability from syntheses of common building blocks to agrochemicals, just to name a few advantages [4][5][6]. From the series of palladium-assisted C–C bond formation, the Sonogashira coupling reaction has been identified as a viable synthetic method for the preparation of various alkenyl- and

• arylacetylenes [7][8] having great importance in organic synthetic schemes of the pharmaceutical industry. From the environmental point of view, the Sonogashira reactions are usually performed in fossil-based common organic reaction media having high vapor pressure even at higher temperatures, toxicity

Chemical tuning of photoswitchable azobenzenes: a photopharmacological case study using nicotinic transmission

• Lorenzo Sansalone,
• Jun Zhao,
• Matthew T. Richers and
• Graham C. R. Ellis-Davies

Beilstein J. Org. Chem. 2019, 15, 2812–2821, doi:10.3762/bjoc.15.274

• perturb all the excellent chemical properties of 2FAB (data not shown). Thus, we synthesized a "4FAB version" of MAHoCh (i.e., 1) as shown in Scheme 1. The synthesis of photochromes 1 and 2 is outlined in Scheme 1. Sonogashira coupling of difluoroiodobenzene and 3-butynol gave 3, which was reduced by

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• to α-pyrones through a consecutive alkynylation–Michael addition–cyclocondensation (AMAC) multicomponent synthesis [23]. The reaction can be rationalized by a Sonogashira coupling between an acid chloride and a terminal alkyne furnishing an alkynone, which is transformed without isolation by addition

Norbornadiene-functionalized triazatriangulenium and trioxatriangulenium platforms

• Roland Löw,
• Talina Rusch,
• Tobias Moje,
• Fynn Röhricht,
• Olaf M. Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1815–1821, doi:10.3762/bjoc.15.175

• decomposition, which is a necessary precondition for ultra-high vacuum STM investigations. The 3-bromo-2-cyano-substituted norbornadiene 4 was synthesized as described in the literature (Scheme 1) [10][11][12]. 4 was converted to 5 with trimethylsilylacetylene (72%) in a Sonogashira cross-coupling reaction. The

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

• . The Pd-catalyzed Sonogashira reaction has successfully constructed arylated internal alkynes that are important intermediates in organic synthesis, molecular electronics and polymers [56]. C–N bond forming reactions between aryl halides and amines/amides/sulfonamides have been extensively studied in

• 2-AP 3 and substituted nitrostyrylisoxazole 48 were used as reaction substrates at 80 °C (Scheme 17) [112]. The method has tolerated a variety of functional groups with good yield. Moreover, highly functionalized imidazo[1,2-a]pyridines have been synthesized by applying a Sonogashira coupling

• Suzuki, Sonogashira and Heck coupling reactions (Scheme 48). The reaction proceeded by the formation of 1-iodoalkyne 142 which was characterized by mass and 1H NMR spetra. This iodoalkyne then formed a complex of Cu(I) with 2-AP. This was followed by migratory insertion of haloalkyne to form reactive Cu