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

• yields (Table 2). Furanocoumarins 3a (angelicin or isopsoralen, Table 2, entry 1) [11][12] and 3c (sphondin, Table 2, entry 3) [59][60] are natural products. They have previously been synthesized from 7-hydroxy-8-iodocoumarins through Sonogashira coupling and cyclization [61] or via Dötz benzannellation

Pd-Catalyzed microwave-assisted synthesis of phosphonated 13α-estrones as potential OATP2B1, 17β-HSD1 and/or STS inhibitors

• Rebeka Jójárt,
• Szabolcs Pécsy,
• György Keglevich,
• Mihály Szécsi,
• Réka Rigó,
• Csilla Özvegy-Laczka,
• Gábor Kecskeméti and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 2838–2845, doi:10.3762/bjoc.14.262

• ). The steric hindrance resulting from the presence of ring B near C-4 might be the main cause for the harsher reaction conditions. This is in agreement with our recently published Sonogashira coupling procedure, which required higher temperatures starting from 4-regioisomers in comparison with those

Synthesis and biological evaluation of 1,2-disubstituted 4-quinolone analogues of Pseudonocardia sp. natural products

• Stephen M. Geddis,
• Teodora Coroama,
• Suzanne Forrest,
• James T. Hodgkinson,
• Martin Welch and
• David R. Spring

Beilstein J. Org. Chem. 2018, 14, 2680–2688, doi:10.3762/bjoc.14.245

• natural products. The chemistry developed towards the allylic alcohols 5 and 6, outlined in Scheme 1, seemed ideal to this end. A range of alkynes 10 could undergo Sonogashira coupling with the commercially available acid chloride 9. The resultant ynones 11 could then undergo conjugate addition with

• shown to be unsuccessful in infecting the lungs of mice [18]. Being able to prevent the production of pyocyanin could therefore be of great therapeutic benefit. Results and Discussion In the implementation of the strategy outlined in Scheme 1, alkynes 10a and 10b were first subjected to Sonogashira

• -quinolone Pseudonocardia sp. natural products, which encompassed variation of both the side chain and N-substituent. This represented an extension of the chemistry which we employed towards the natural products, utilising sequential Sonogashira coupling, high-yielding conjugate addition, and metal-catalysed

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• motif were prone to aromatization and had to be protected from contact with air and higher temperatures. Removal of solvents was performed below 21 °C and all compounds were stored under argon at −18 °C. Sonogashira coupling (PdCl2(PPh3)2) of dienol triflate 11 with alkyne 12 [11] provided C20 ester 13

• place. Thus, we reduced the ester function of dienol triflate 11 to the alcohol (DIBAL-H, DCM, −78 °C), followed by oxidation to aldehyde 15 (IBX, Scheme 2). Fortunately, the cyclohexadiene moiety survived the oxidation conditions, which was not the case when using PCC or MnO2. Subsequent Sonogashira

• )-isomer of 24, compound 31, via Sonogashira coupling with the (E)-isomer [11] of 12. Chlorinated allene 32 was formed from 31 as the only product on treatment with SOCl2/pyridine, presumably after chlorosulfonation, followed by chlorine transfer and loss of SO2 (Scheme 5). There is precedence that

Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• %) together with the dimeric side product 3 (4.5%, Scheme 1) [37]. The moderate yield of the 5’azido-dC derivative results from incomplete conversion. Possibly, traces of copper used for the Sonogashira cross coupling and high substrate concentration were initiating dimerization of azide 2. Nevertheless, an

Practical tetrafluoroethylene fragment installation through a coupling reaction of (1,1,2,2-tetrafluorobut-3-en-1-yl)zinc bromide with various electrophiles

• Ken Tamamoto,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2018, 14, 2375–2383, doi:10.3762/bjoc.14.213

• % isolated yield. Then, 4t underwent Pd(0)-catalyzed Sonogashira cross-coupling reaction with phenylacetylene, producing the corresponding tolane derivative 4u with a CF2CF2 fragment in good yield (30% overall yield from 2-Zn). Consequently, 2-Zn is found to be a powerful tetrafluoroethylenating agent for

Coordination-driven self-assembly of discrete Ru₆–Pt₆ prismatic cages

• Aderonke Ajibola Adeyemo and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2018, 14, 2242–2249, doi:10.3762/bjoc.14.199

• mass spectrometry, and UV–vis analysis. Further structural insights were revealed by computational studies. Results and Discussion The triplatinum metalloligand 2 was synthesized through a four-step reaction involving a Sonogashira coupling (Scheme 2) and the crude product was purified by column

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• the 1,6-enynes from the corresponding 2-halogenated phenols, benzenethiols or anilines, via a simple substitution–elimination–Sonogashira synthetic sequence. In addition, the group has synthesised trifluoromethylated modified versions of certain drugs (Figure 13). Variations on the classical

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• -Arylbenzo[b]quinolizinium derivatives were prepared with base-free Suzuki–Miyaura coupling reactions between benzo[b]quinolizinium-9-trifluoroborate and selected benzenediazonium salts. In addition, the Sonogashira coupling reaction between 9-iodobenzo[b]quinolizinium and the arylalkyne derivatives yielded

• ]quinolizinium derivatives with a large extension of the π-system, which should provide promising properties as G4-DNA ligands, we also focused our attention on the Sonogashira reaction as synthetic route to arylalkynyl-substituted derivatives. In this case, we aimed at donor-substituted derivatives such as 2b–d

• since they were proposed to have ideal photophysical and DNA-binding properties. Herein, we present the successful Suzuki–Miyaura and Sonogashira coupling reactions of benzo[b]quinolizinium substrates. In addition, the absorption and emission properties of the novel arylalkynylbenzo[b]quinolizinium

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• catalyzed cascade reaction to afford alkylidenefluorenes 49 (Scheme 17) [57]. In terms of mechanism, a Pd(0)/Cu(I)-catalyzed Sonogashira coupling reaction from the iodonium salt 48 delivers a 2-alkynyl-2’-iodoarene 50 that, then, cyclizes to 51 via insertion of the Pd(0) species into the iodoarene moiety

• –I motif (Scheme 22) [62]. Hence aryl- and alkyl-substituted terminal alkynes can be coupled via a Sonogashira reaction when PPh3 is used as ligand, while the use of diphenylphosphinoferrocenyl ligand (dppf) allows the Heck-type coupling of acrylates, vinyl ketones and electron-poor styrene

• -λ3-iodanes (Scheme 23) [63]. The first step relies on the copper-catalyzed coupling between an anthranilic acid derivative and the biphenyl moiety. The resulting iodoarene product is then submitted to a Sonogashira coupling reaction, allowing the one-pot preparation of a library of biphenyl products

Atom-economical group-transfer reactions with hypervalent iodine compounds

• Andreas Boelke,
• Peter Finkbeiner and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108

• incorporated into the final product, the calculated AE (46% for R1 = R2 = H, R3 = Ar = Ph) is close to the procedures of Panda and Xie due to lower PIDA loadings. A metal-catalysed procedure for the atom-economical utilization of (dicarboxyiodo)benzenes 20 in a tandem C(sp3)–H amination/sila-Sonogashira

• iodoarenes 32. These species smoothly underwent subsequent Suzuki–Miyaura, Sonogashira and Mirozoki–Heck couplings. The respective arylated, alkynylated and alkenylated products 33a–d were obtained in high yields with excellent stereoselectivity. Due to the intramolecular pathway of the first step, high AE

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

• benzotropylium ion 45. Secondly, 11 is obtained in 18% yield after benzylic bromination of 42 with NBS, followed by in situ elimination reaction of the labile bromide 43 mediated by t-BuOK (Scheme 9). Palladium-catalyzed C–C bond-formation reactions such as Heck and Sonogashira couplings are employed in a wide

• variety of areas in organic chemistry [56][57]. Recently, Shaabani’s group synthesized and characterized palladium nanoparticles supported on ethylenediamine-functionalized cellulose (PdNPs@EDACs) as a novel bio-supported catalyst for Heck and Sonogashira couplings in water [58]. Shaabani’s group reported

The first Pd-catalyzed Buchwald–Hartwig aminations at C-2 or C-4 in the estrone series

• Ildikó Bacsa,
• Dávid Szemerédi,
• János Wölfling,
• Gyula Schneider,
• Lilla Fekete and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 998–1003, doi:10.3762/bjoc.14.85

• (dba)3 as catalysts, X-Phos as a ligand, Cs2CO3 as a base in toluene or DMF solvent under thermal heating or microwave irradiation [18]. We recently described halogenations [19] and Sonogashira couplings on ring A of 13α-estrone and its 3-methyl ether [20]. The 13-epimer of natural estrone is a non

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• hydrophobic membrane and as a consequence a higher reaction rate. Dergunov et al. reported on the design of a porous polymeric nanoreactor with a lipid bilayer for coupling reactions [87]. These nanocapsules were loaded with palladium catalysts and successfully used in Suzuki, Sonogashira and Heck cross

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• ]pyrimidine derivatives 105 which were subsequently used to prepare alkynyl alcohol 111 derivatives of pyrazolo[1,5-a]pyrimidines 106 by a Sonogashira coupling in 69–94% yields. Fluorodeoxygention of 106 using deoxofluor afforded fluoropropynyl-substituted pyrazolo[1,5-a]pyrimidine 107 with variable

Asymmetric synthesis of propargylamines as amino acid surrogates in peptidomimetics

• Matthias Wünsch,
• David Schröder,
• Tanja Fröhr,
• Lisa Teichmann,
• Sebastian Hedwig,
• Nils Janson,
• Clara Belu,
• Jasmin Simon,
• Shari Heidemeyer,
• Philipp Holtkamp,
• Jens Rudlof,
• Lennard Klemme,
• Alessa Hinzmann,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2017, 13, 2428–2441, doi:10.3762/bjoc.13.240

• cycloaddition, CuAAC and RuAAC), the thiol–yne reaction, Diels–Alder reactions and the Sonogashira cross-coupling. While amino acids with a terminal alkyne in the side chain are well-known, the synthesis of their correlates where the carboxy group is replaced by a terminal alkyne is still tedious. Nevertheless

• in p- or m-position were reacted with propargyl alcohol in a Sonogashira reaction to give the phenylpropargyl alcohols 1a and 1b (Figure 4) [42][43], which were transformed in a Swern oxidation to afford the aldehydes 2a and 2b [44]. Condensation of the aldehydes 2a and 2b with (R)-configured tert

• fluoride leads to deprotonation in the Cα-position of 6i, 6k and 6j, inducing an alkyne rearrangement to form an allene, which rearranges further to provide an α,β-unsaturated imine (Figure 8) [97]. One target application of propargylamines 7 is the Sonogashira cross-coupling with halogenated benzoates

Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

• Jan Podlesný,
• Lenka Dokládalová,
• Oldřich Pytela,
• Adam Urbanec,
• Milan Klikar,
• Numan Almonasy,
• Tomáš Mikysek,
• Jaroslav Jedryka,
• Iwan V. Kityk and
• Filip Bureš

Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235

• boron derivatives [34][35]. Twofold Sonogashira cross-coupling was utilized towards chromophores 1b–5b. All cross-coupling reactions were carried out in THF with PdCl2(PPh3)2 as palladium precatalyst. The reaction time was approximately 24 hours to achieve sufficient conversion (32–73%). Despite bearing

• in modular way prepared by Suzuki–Miyaura, Migita–Stille, and Sonogashira cross-coupling reactions. The chromophores differ in the π-system extension as well as in the peripheral substitution. The thermal stability of 1–5 is mostly affected by the presence of acetylene linkers, 1,4-phenylene and 2,5

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• diacetylene linkers, via a butadiyne and via an aryldiacetylene moiety (Figure 2). Such binuclear phthalocyanines that are connected via a rigid acetylene linker synthesized by Glaser or Sonogashira reactions have attracted attention due to their interesting effects resulting from further expansion of

• under Sonogashira cross-coupling conditions (Scheme 6). UV–vis absorption measurements suggested that the deoxyribonucleoside-linked TFEO-Pcs had a non-aggregation property, as expected. Unfortunately, it was also found that these conjugates gradually decomposed under light irradiation, so their

Novel approach to hydroxy-group-containing porous organic polymers from bisphenol A

• Tao Wang,
• Yan-Chao Zhao,
• Li-Min Zhang,
• Yi Cui,
• Chang-Shan Zhang and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 2131–2137, doi:10.3762/bjoc.13.211

• organic polymers (POPs) have been reported via Sonogashira–Hagihara coupling reaction [16], Suzuki–Miyaura chemistry [17], Yamato reaction [18], and self condensation of aromatic nitriles[19]. Although these methods can be used to construct POPs with high specific surface area values, these reactions are

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• of styrenes with aryl bromides or aryl chlorides (Scheme 9) [59]. Sonogashira reaction Stolle and co-workers have reported a Sonogashira coupling reaction under ball milling conditions in which the reactions were done in absence of any copper catalyst or any additional ligands [60]. In presence of

• palladium salts (Pd(OAc)2 or Pd(PPh3)4) and DABCO (1,4-diazabicyclo[2.2.2]octane) various acetylenes and aryl halides were coupled to obtain the Sonogashira coupling products in excellent yields (near quantitative, Scheme 10a). The reactions were reported for aliphatic alkynes as well. In Scheme 10b, an

• example of a double Sonogashira reaction is shown [60]. Oxidative cross-dehydrogenative coupling Copper-catalyzed mechanochemical oxidative cross-dehydrogenative coupling (CDC) reactions [61][62][63][64][65][66] of tetrahydroisoquinolines with alkynes and indoles was reported by Su and co-workers (Scheme

Synthesis of benzothiophene and indole derivatives through metal-free propargyl–allene rearrangement and allyl migration

• Jinzhong Yao,
• Yajie Xie,
• Lianpeng Zhang,
• Yujin Li and
• Hongwei Zhou

Beilstein J. Org. Chem. 2017, 13, 1866–1870, doi:10.3762/bjoc.13.181

• heterocycles are not well-documented [30][31]. Recently, our group explored the utilization of β-sulfonium carbanions for the preparation of thiophene derivatives [19]. Alkynes were treated with acyl chloride under Sonogashira reaction conditions and the expected β-sulfonium carbanions were obtained in a one

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• such as Heck, Suzuki, Sonogashira and Glaser reactions are still unusual methods for the formation of C–C bonds [1][2][3][4][5][6][7], but the method arouse considerable attention because of an environmentally benign and solvent-free synthesis approach as well as high efficiency and good atom economy

• –C cross coupling [13][14][15][16] reactions but also in mechanically activated Heck [4][17][18][19][20][21][22], Suzuki [23][24][25][26], and Sonogashira [5][27][28] coupling reactions. The limitations of which are obviously unstable ligands and expensive Pd catalysts. Furthermore, the contamination

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

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

• 10.3762/bjoc.13.126 Abstract Novel 13α-estrone derivatives were synthesized by Sonogashira coupling. Transformations of 2- or 4-iodo regioisomers of 13α-estrone and its 3-methyl ether were carried out under different conditions in a microwave reactor. The 2-iodo isomers were reacted with para-substituted

• 17β-HSD1 inhibitors, displaying submicromolar IC50 values. Keywords: benzofuran; 13α-estrone; 17β-HSD1 inhibition; partial saturation; Sonogashira coupling; Introduction Synthetic modifications of the naturally occurring female prehormone estrone may lead to compounds with diverse biological

• -catalyzed C–C coupling reactions. Some Sonogashira couplings on estrane, but not on the 13α-estrane core have been performed at C-2, -3, -11, -16 and -17. To the best of our knowledge, 4-coupled regioisomers have not been synthesized to date [19]. Couplings of steroidal alkynes with small molecular halides

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

• ) was the installation of the side chain at C1–C13. The synthesis relied on two consecutive Sonogashira–Hagihara cross-coupling reactions that provided the ene–diyne system (C10–C15) 10 in good yield. However, partial hydrogenation (only the zinc–copper couple worked) furnished the desired (Z,E,Z

• first synthesis of elansolid B2 (3). The key for improvement was to abandon the two Sonogashira reactions along with the syn-reductions of the two alkynes. Instead, we planned to utilize the Suzuki–Miyaura and the Stille reactions and two Z-configured vinyl iodides to assemble the (Z,E,Z)-triene unit