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

• ]. Mechanochemical Suzuki reaction [56]. Mechanochemical Suzuki–Miyaura coupling by LAG [57]. Mechanochemical Heck reaction [59]. a) Sonogashira coupling under milling conditions. b) The representative example of a double Sonogashira reaction of p-iodoacetophenone with 1,4-bis-ethynyl benzene. Copper-catalyzed CDC

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

• was to develop facile and effective Sonogashira coupling methods for the preparation of 2- or 4-phenethynyl derivatives in the 13α-estrone series. 2- or 4-iodo-13α-estrone and their 3-methyl ethers were chosen as starting compounds. The partial or full saturation of the C≡C bond of certain 2- or 4

Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties

• Işıl Yenice,
• Sinan Basceken and
• Metin Balci

Beilstein J. Org. Chem. 2017, 13, 825–834, doi:10.3762/bjoc.13.83

• 9. Substituted alkyne derivatives 10a and 10b were synthesized according to the literature. The Sonogashira coupling reaction [25] of aryl iodides with terminal acetylene is an effective approach towards the synthesis of substituted arylalkynes. The reaction of 1-iodo-4-methoxybenzene and 1-iodo-4

• -nitrobenzene with trimethylsilylacetylene under the Sonogashira coupling conditions followed by hydrolysis of the trimethylsilyl groups with K2CO3 resulted in the formation of 10a and 10b [26][27][28]. Fortunately, terminal alkynes can be easily converted into bromoalkynes with N-bromosuccinimide in the

Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions

• Michal Medvecký,
• Igor Linder,
• Luise Schefzig,
• Hans-Ulrich Reissig and
• Reinhold Zimmer

Beilstein J. Org. Chem. 2016, 12, 2898–2905, doi:10.3762/bjoc.12.289

• -iodo-substituted 1,2-oxazines 4, we turned our attention to their conversion into subsequent products by taking advantage of the alkenyl iodide functionality for various palladium-catalyzed cross-coupling reactions. As a first approach to form a new C–C bond at C-5 we envisioned the Sonogashira

• coupling. For this purpose, we selected (trimethylsilyl)acetylene as alkyne component. The Sonogashira couplings of 5-iodo-1,2-oxazines syn-4a and anti-4a were carried out under standard conditions using a catalytic system consisting of PdCl2(PPh3)2, CuI and triethylamine in toluene at room temperature to

Symmetry-based approach to oligostilbenoids: Rapid entry to viniferifuran, shoreaphenol, malibatol A, and diptoindonesin G

• Youngeun Jung,
• Dileep Kumar Singh and
• Ikyon Kim

Beilstein J. Org. Chem. 2016, 12, 2689–2693, doi:10.3762/bjoc.12.266

• natural oligostilbenoids guided us to design a modular synthetic approach to these molecules by utilizing a three-step sequence consisting of Sonogashira coupling, iodocyclization, and Suzuki coupling. During our synthesis, the relative reactivities of ester, aldehyde, and alkoxy groups on the same aryl

• element [19] of the target molecules. We expected that the key intermediate (inset box of Scheme 1) could be constructed from the monoiodo compounds 1, 2, or 3 through a sequence involving Sonogashira coupling, iodocyclization [20][21][22][23][24][25][26], and Suzuki coupling. As the starting materials (1

• -dimethoxybenzaldehyde, and 3,5-dimethoxybenzyl alcohol under the influence of either I2/silver trifluoroacetate or N-iodosuccinimide afforded 1 [32][33][34], 2 [35], and 7 [36][37], respectively (Scheme 2). The hydroxy group of 7 was protected as an acetate, providing 3 in 96% yield. Sonogashira coupling of the

A versatile route to polythiophenes with functional pendant groups using alkyne chemistry

• Xiao Huang,
• Li Yang,
• Rikard Emanuelsson,
• Jonas Bergquist,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 2682–2688, doi:10.3762/bjoc.12.265

• alkyne chemistry. Its usefulness is demonstrated by a series of functionalized polythiophene derivatives that were obtained by pre- and post-electropolymerization transformations, provided by the synthetic ease of the Sonogashira coupling and click chemistry. Keywords: electropolymerization; functional

• polymers; polythiophene; Sonogashira coupling; thiophene; Introduction Currently organic conjugated polymers are attracting considerable interest for various applications in plastic electronics. In particular, poly(3,4-ethylenedioxythiophene) (PEDOT) [1] and its derivatives [2][3][4][5][6][7] play an

• the nitrogen atom. As shown by our synthesis, all of these electron acceptor units were tolerant to Sonogashira coupling conditions, which produced new EDOT derivatives 9, 10, 11 and 12 (Scheme 4). The Sonogashira couplings were performed between the alkyne terminal of pyEDOT and a brominated ring

Solvent-free, visible-light photocatalytic alcohol oxidations applying an organic photocatalyst

• Martin Obst and
• Burkhard König

Beilstein J. Org. Chem. 2016, 12, 2358–2363, doi:10.3762/bjoc.12.229

• for mechanochemical syntheses include stoichiometric reactions such as the Knoevenagel condensation and the Wittig reaction, but also reactions catalyzed by metal catalysts, like the Sonogashira coupling and the Suzuki coupling [1]. Photocatalysis, as a part of Ostwald’s sub-discipline photochemistry

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

• Forrest S. Etheridge,
• Roshan J. Fernando,
• Sandra Pejić,
• Matthias Zeller and
• Geneviève Sauvé

Beilstein J. Org. Chem. 2016, 12, 1925–1938, doi:10.3762/bjoc.12.182

• -phenylacetylene analogs afforded the WS3 derivatives in good yield (Scheme 1). We chose to utilize Stille coupling instead of Sonogashira coupling because we had previously found that this method gives higher yields for installing phenylethynyl pyrrolic substituents [9]. The fluorinated tributyltinphenylacetylene

Practical synthetic strategies towards lipophilic 6-iodotetrahydroquinolines and -dihydroquinolines

• David R. Chisholm,
• Garr-Layy Zhou,
• Ehmke Pohl,
• Roy Valentine and
• Andrew Whiting

Beilstein J. Org. Chem. 2016, 12, 1851–1862, doi:10.3762/bjoc.12.174

• literature [13]. An initial investigation with the corresponding bromides indicated that these were unreactive towards many cross-coupling methodologies, presumably due to the highly electron-rich arene [14]. Reactions such as the Sonogashira coupling, for example, often required high catalyst loadings

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• one-pot reaction of 2-bromobenzaldehydes 169, alkynes 170, amines 171, and diethyl phosphonate under multicatalytic conditions including palladium and copper salts (Scheme 37) [75]. This process presumably involves a sequential Sonogashira coupling/cyclization-nucleophilic addition reaction, which is

Study on the synthesis of the cyclopenta[f]indole core of raputindole A

• Nils Marsch,
• Mario Kock and
• Thomas Lindel

Beilstein J. Org. Chem. 2016, 12, 334–342, doi:10.3762/bjoc.12.36

• %, three steps, Scheme 3). Sonogashira coupling occurred preferably at the iodinated 6-position affording 6-alkynylindole 20 after desilylation (56%). The reaction with ketone 6 after magnesiation led to propargylic alcohol 23 (50%). Interestingly, the Meyer–Schuster rearrangement of triflated alkyne 23 to

• %) was synthesized by Sonogashira coupling of N-TIPS-6-iodoindoline (39) and 42. Conversion of 43 to the (Z)-allylic alcohol 44 by modified (K2CO3) Lindlar hydrogenation (47%) followed. Treatment of 44 with SnCl4 in DCM afforded cyclopenta[f]indoline 45, albeit in the rather disappointing yield of 11%. A

Hydroquinone–pyrrole dyads with varied linkers

• Hao Huang,
• Christoffer Karlsson,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 89–96, doi:10.3762/bjoc.12.10

• Sonogashira coupling reaction (Scheme 3). Thus, 2,5-dimethoxyphenyl bromide (8) was converted to ((2,5-dimethoxyphenyl)ethynyl)trimethylsilane (9), which was desilylated by addition of NaOH (aq) to give 2-ethynyl-1,4-dimethoxybenzene (10). Sonogashira conditions were as described by Erdélyi et al. using

Solving the puzzling competition of the thermal C²–C⁶ vs Myers–Saito cyclization of enyne-carbodiimides

• Anup Rana,
• Mehmet Emin Cinar,
• Debabrata Samanta and
• Michael Schmittel

Beilstein J. Org. Chem. 2016, 12, 43–49, doi:10.3762/bjoc.12.6

• in the Myers–Saito pathway. The synthetic strategy (Scheme 3) was to first prepare carbodiimide 10 [24] according to a literature procedure. In the next step, a Sonogashira coupling between 10 and N,N-dimethylprop-2-yn-1-amine afforded the desired enyne-carbodiimide 11 in 24% yield. Thermolysis of 11

Asymmetric 1,4-bis(ethynyl)bicyclo[2.2.2]octane rotators via monocarbinol functionalization. Ready access to polyrotors

• Cyprien Lemouchi and
• Patrick Batail

Beilstein J. Org. Chem. 2015, 11, 1881–1885, doi:10.3762/bjoc.11.202

• variety of functionalization sequences of BCO rotators by performing nucleophilic reactions on the terminal alkyne [16] as well as Sonogashira coupling reactions [17]. One way to synthesize 1 is via a catalytic reaction to achieve the deprotection of a single 2-methyl-3-butyn-2-ol and transform the

• or 8 by Sonogashira coupling reactions (Scheme 4). Route 1 was preferred on account of higher yields. The ester function is necessary to purify the intermediate 13 and isolate 14 with excellent purity. These results demonstrate the viability of our approach of the desymmetrization of 1,4-bis(ethynyl

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• polymer 1d, which was obtained by Sonogashira coupling of 1b with 1e and exhibited a partial solubility in THF with Mw = 610000 Da (THF soluble fraction) [43] (Scheme 1). Polymer properties in the solid state are hugely important for organic electronics applications, with the electronic properties of

SmI₂-mediated dimerization of indolylbutenones and synthesis of the myxobacterial natural product indiacen B

• Nils Marsch,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2015, 11, 1700–1706, doi:10.3762/bjoc.11.184

• Nicolaou and Procter [31][32]. The pattern of geometrical [3 + 2] cycloaddition was also obtained with inverted enone moieties. 6-Prenoylindole (14) was synthesized in two steps from 6-iodoindole (4) by Sonogashira coupling with propargylic alcohol 12 and subsequent Meyer–Schuster rearrangement [33

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• in solution and in the solid state even in neutral state [18]. Compounds 22 and 23 were synthesized in good yields by Sonogashira coupling reaction of 1,3,5-triethynylbenzene with 20 and 1,3,5-triiodobenzene with 21, respectively (Scheme 1). X-ray analysis of 22 revealed the columnar structure, in

• )[12]annulenes 28 and 29 were pepared by Sonogashira coupling of 26 with 24 and 27 with 25 in 25 and 36% yields, respectively. For the synthesis of 30 and 31, cyclotrimerization of 24 and 25 with a stoichiometric amount of PdCl2(PPh3)2 and CuI in triethylamine–THF was employed to afford 30 and 31 in 32

• cyclic conjugation and the interaction of the two TTF units in the neutral and cationic states, TTF-fused annulenes 33 [69] and radiannulenes 34 and 35 [70] were synthesized using a Sonogashira coupling in moderate yields (Figure 9). The thermodynamic study on the self-aggregation of tris(TTF)annulenes

Synthesis and spectroscopic properties of β-triazoloporphyrin–xanthone dyads

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2015, 11, 1434–1440, doi:10.3762/bjoc.11.155

• -diethynylxanthen-9-one (11) was synthesized in three steps from 3,6-dihydroxyxanthen-9-one (8) as a starting material. The first step involved the reaction of xanthone (8) with triflic anhydride in CH2Cl2 containing pyridine at 0 °C to afford 3,6-di-OTf-xanthone [52] (9). Subsequent Sonogashira coupling with

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• moderate yield. RCM of the diene derived from the dialdehyde 111 afforded the macrocyclic cyclophane 113 as a less strained product (Scheme 16). Sonogashira coupling: Wegner and co-workers [125] have reported the synthesis of cyclophanes 122a–c via Sonogoshira coupling [126] (Scheme 17). To this end, the

The synthesis of active pharmaceutical ingredients (APIs) using continuous flow chemistry

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 1194–1219, doi:10.3762/bjoc.11.134

Chiroptical properties of 1,3-diphenylallene-anchored tetrathiafulvalene and its polymer synthesis

• Masashi Hasegawa,
• Junta Endo,
• Seiya Iwata,
• Toshiaki Shimasaki and
• Yasuhiro Mazaki

Beilstein J. Org. Chem. 2015, 11, 972–979, doi:10.3762/bjoc.11.109

• process as shown in Scheme 1. Thus, starting with 1-(4-bromophenyl)-2-methylpropanone (4), which was prepared from bromobenzaldehyde (see Supporting Information File 1), which upon treatment with lithium acetylide at low temperature gave racemic propargyl alcohol 5 in 94% yield. Sonogashira coupling

Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores

• Huixin Jiang,
• Virginia Mazzanti,
• Christian R. Parker,
• Søren Lindbæk Broman,
• Jens Heide Wallberg,
• Karol Lušpai,
• Adam Brincko,
• Henrik G. Kjaergaard,
• Anders Kadziola,
• Peter Rapta,
• Ole Hammerich and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104

• conjugated buta-1,3-diynediyl bridge between the two TTFs. Results and Discussion Synthesis The synthesis of 4 and 5 was accomplished according to Scheme 1 starting from the known TTF-iodide 9, readily prepared from compound 3b [16]. A Sonogashira coupling with trimethylsilylacetylene gave 10 that after

• desilylation was either subjected to a Sonogashira coupling with 9 to give 4 or to an oxidative Hay coupling to give 5 – using recently developed conditions where 4 Å molecular sieves were added to the reaction mixture to remove water [17]. Compounds 6 and 7 were prepared by treating 9 with either the trans

• -TEE 11 [18] or 2,6-diethynylpyridine 12 in Sonogashira coupling reactions (Scheme 2). The unsymmetrical radiaannulene 8 was prepared according to Scheme 3. The TEE-TTF derivative 13 [15] was reacted in a Sonogashira coupling with an excess of trimethylsilylacetylene to furnish the product 14. Removal

Gold-catalyzed formation of pyrrolo- and indolo-oxazin-1-one derivatives: The key structure of some marine natural products

• Sultan Taskaya,
• Nurettin Menges and
• Metin Balci

Beilstein J. Org. Chem. 2015, 11, 897–905, doi:10.3762/bjoc.11.101

• and N-propargylindole-2-carboxylic acids 37, 41 and 45, which were synthesized by hydrolysis of the corresponding esters (Table 2). The Sonogashira cross-coupling reaction [56][57][58][59][60][61] was used for the synthesis of the desired starting materials 29 and 33. For the Sonogashira coupling

Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s

• Natalia A. Danilkina,
• Petr S. Vlasov,
• Semen M. Vodianik,
• Andrey A. Kruchinin,
• Yuri G. Vlasov and
• Irina A. Balova

Beilstein J. Org. Chem. 2015, 11, 373–384, doi:10.3762/bjoc.11.43

• ethynylene)s comprising a cinnoline core were prepared in high yields via a three-step methodology. A Richter-type cyclization of 2-ethynyl- and 2-(buta-1,3-diynyl)aryltriazenes was used for cinnoline ring formation, followed by a Sonogashira coupling for the introduction of trimethylsilylethynyl moieties

• and a sila-Sonogashira coupling as the polycondensation technique. The fluorescence of the cinnoline-containing polymers in THF was highly sensitive to quenching by Pd2+ ions. Keywords: cinnolines; fluorescence quenching; Pd2+ detection; poly(arylene ethynylene)s; Sonogashira coupling; Introduction

• -dibromocinnolines 4a,b (Table 1). Triazenes 3a,b were synthesized from 4-bromo-2-iodophenyltriazene 1 by the Sonogashira coupling [44][45] with hexyne (2a) and TMS-protected diacetylene 2b using conditions for the one-pot TMS group removal and the Sonogashira coupling developed recently [46]. The last reaction