Reactivity studies of pincer bis-protic N-heterocyclic carbene complexes of platinum and palladium under basic conditions

• David C. Marelius,
• Curtis E. Moore,
• Arnold L. Rheingold and
• Douglas B. Grotjahn

Beilstein J. Org. Chem. 2016, 12, 1334–1339, doi:10.3762/bjoc.12.126

• and of the C–H bond of acetylene. The same ligand in CpRu complexes 2 and 3 showed heterolysis of dihydrogen [13]. 1 had a much faster ligand exchange rate after ionization as compared to the Cp*Ir analog (ethylene bound in 5 min at rt (CpRu) instead of 16 h at 70 °C (Cp*Ir)). Species 1 could be

Reactions of N,3-diarylpropiolamides with arenes under superelectrophilic activation: synthesis of 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones and their derivatives

• Larisa Yu. Gurskaya,
• Diana S. Belyanskaya,
• Dmitry S. Ryabukhin,
• Denis I. Nilov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 950–956, doi:10.3762/bjoc.12.93

• [4][5]. Many of these synthetical protocols are based on alkynes, which are widely used for the preparation of various carbo- and heterocycles [6][7][8][9][10]. Based on our works on the synthesis of 4-arylquinolin-2(1H)-ones from acetylene compounds under superelectrophilic activation conditions [11

• Discussion The protonation of alkynamides 1 on both the oxygen atom of the amide group and a carbon atom of the acetylene bond in superacids or coordination of these basic centers with strong Lewis acids leads to the formation of dications A that are considered as superelectrophiles [15] (Scheme 1). These

• phenyl group). Amides 1, bearing various donor (Me, MeO, benzo-) and acceptor (F, Cl) substituents on both aryl rings at the acetylene bond and at the nitrogen atom may be involved in this reaction. Substrates 1g, 1h, having electron withdrawing 4-F and 4-Cl substituents on the N-aryl ring, were hardly

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

• included the second indole moiety of raputindole A (1). Boc protection of 6-iodoindole (2) [35], Sonogashira reaction of 3 with TMS-acetylene, and desilylation gave the N-protected alkynylindole 4 in excellent yield (Scheme 2). Boc-iodoindole 3 was also the precursor of the coupling partner, ketone 6

• Chancellor and coworkers [42], gave nitrophenol 11 in a reasonable yield (45%). The Batcho–Leimgruber protocol failed for nitrophenol 11 [43]. However, after O-benzylation of 11 to 12, Boc-indole 15 was obtained in the very good yield of 91%. Coupling with TMS-acetylene was followed by desilylation to obtain

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

• material for the corresponding phosphonate. However, neither n-BuLi nor t-BuOK used as base succeeded to give the desired product. Acetylene linker: Synthesis of 3-((2,5-dimethoxyphenyl)ethynyl)-1H-pyrrole (3d) The synthesis strategy for the ethynyl-linked compound 3d was straightforward, using a

Enantioselective additions of copper acetylides to cyclic iminium and oxocarbenium ions

• Jixin Liu,
• Srimoyee Dasgupta and
• Mary P. Watson

Beilstein J. Org. Chem. 2015, 11, 2696–2706, doi:10.3762/bjoc.11.290

• terminal alkyne to the enamine simultaneously generates the copper acetylide and iminium ion, which are proposed to both bind to the chiral copper catalyst (see 4). A broad scope in the acetylene was observed, with arylalkynes resulting in the highest ee’s. To our knowledge, these were the first

• reaction time could be reduced. Addition of alkynes with aryl, alkyl and trimethylsilyl substituents were successful, with the highest enantioselectivity observed when (trimethylsilyl)acetylene was used (94% ee). Just before Li’s report of the alkynlation of N-arylisoquinolinium ions, Taylor and Schreiber

• reported a CuBr/Quinap-catalyzed alkynylation of N-alkylisoquinolinium ions (Scheme 5) [25]. Similar to Li’s alkynylation of N-arylisoquinolinium ions, alkynes with various substituents can be used successfully, and the highest ee’s were observed when (trimethylsilyl)acetylene was used (99% ee). Most of

Lewis acid-promoted hydrofluorination of alkynyl sulfides to generate α-fluorovinyl thioethers

• Davide Bello and
• David O'Hagan

Beilstein J. Org. Chem. 2015, 11, 1902–1909, doi:10.3762/bjoc.11.205

• somewhat scarce. The only account we are aware of involves the AIBN-promoted thiodesulfonylation of aromatic fluorovinyl sulfones as reported by Wnuk [12], a reaction which works in varying yields and stereoselectivities. Following from our previous experience [7] with terminal acetylene thioethers, we now

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

• -deficient acetylene compounds (Scheme 6). By reacting 23 with 24a this method provides diester 25a in good yield [63]. Compound 25a can be reduced to diol 25d [64] and further converted by either the Appel method [59] or by reaction with PBr3 [65] into dibromomethyl compound 21, which is required for

• synthetic pathway A. Even though the reaction of 23 with acetylene compound 24b (containing only one electron-withdrawing group) is efficient, affording 25b with a 60% yield [66], attempts to invoke cycloaddition of 23 and 24c in a similar manner led to a poor yield of 25c (8%) [60]. An efficient method for

Synthesis of alpha-tetrasubstituted triazoles by copper-catalyzed silyl deprotection/azide cycloaddition

• Zachary L. Palchak,
• Paula T. Nguyen and
• Catharine H. Larsen

Beilstein J. Org. Chem. 2015, 11, 1425–1433, doi:10.3762/bjoc.11.154

• Scheme 1 would streamline the synthesis of alpha-tetrasubstituted triazoles 6. In the first step, our solvent-free copper-catalyzed three-component coupling of cyclohexanone (1), amines 2, and alkynes 3 provides high yields of silyl-protected propargylic amines 4 [24][25]. Trimethylsilyl (TMS) acetylene

• was not stable in the presence of the copper(II) chloride catalyst, and triethylsilylacetylene did not convert cleanly to product. Triisopropylsilyl (TIPS) acetylene was found to be superior to tert-butyldimethylsilylacetylene as a source of silylated tetrasubstituted propargylic amines. Although TMS

• starting materials, cyclohexanone (1), 4-methylpiperidine (2a), and TIPS-acetylene (3). As there are no added ligands, solvents, promoters, or excess starting materials, the sole byproduct in the formation of tetrasubstituted propargylamine 4a is one equivalent of water [25]. The second step links silyl

Synthesis of γ-hydroxypropyl P-chirogenic (±)-phosphorus oxide derivatives by regioselective ring-opening of oxaphospholane 2-oxide precursors

• Iris Binyamin,
• Shoval Meidan-Shani and
• Nissan Ashkenazi

Beilstein J. Org. Chem. 2015, 11, 1332–1339, doi:10.3762/bjoc.11.143

• . Further heating did not provide higher conversion. Following hydrolytic work-up and flash chromatographic purification the product was identified as allene 5f, rather than acetylene 5h, due to propargyl–allene rearrangement (Scheme 5). Most characteristic are the 13C NMR chemical shift of HC=C=CR at

• serve as the catalytic base that prompts the rearrangment. The 1,3-hydrogen shift in a P-propargyl system is well established [51]. In an attempt to prevent this rearrangement we applied an acetylene substituted with the bulky TMS group [58], which may be easily removed at a later stage, and formed the

• formed regioselectivly. Synthesis of acetylene and allene phosphine oxides. Synthesis of γ-hydroxypropyl (±)-phosphinatesa and related compounds. Synthesis of γ-hydroxypropyl (±)-phosphine oxidesa. Supporting Information Supporting Information File 66: Experimental details, characterization data and 1H

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

• Glaser–Eglinton coupling of the terminal acetylene groups provided complex 49 in 47% yield as fine, deep maroon crystals. In connection with the cyclophane synthesis, Kotha and Waghule [92] demonstrated the use of the Glaser–Eglinton coupling as a key step. The dipropargylated compound 51 was subjected

Self-assembly of heteroleptic dinuclear metallosupramolecular kites from multivalent ligands via social self-sorting

• Christian Benkhäuser and
• Arne Lützen

Beilstein J. Org. Chem. 2015, 11, 693–700, doi:10.3762/bjoc.11.79

• (trimethylsilyl)acetylene into 7 in a yield of 85% [27]. Alkyne 7 was then subjected to a Negishi reaction with 2-bromopyridine (8) derived zinc organyl 9 to give the silyl-protected ethynylated bipyridine 10 in excellent yield of 99% which was subsequently desilylated under standard conditions to give terminal

Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

• Grzegorz Mlostoń,
• Paulina Grzelak,
• Maciej Mikina,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2015, 11, 576–582, doi:10.3762/bjoc.11.63

• acetylenic dienophiles, other easily available acetylenes were used in the reaction with 1a. In all reactions attempted with phenylacetylene, (pyridin-2-yl)acetylene, and (tert-butyl)acetylene, no conversion of 1a was observed as evidenced by the blue color of the reaction mixture even after 24 h

• . Unfortunately, the experiments performed under the described conditions (THF, LiClO4, temp.) with (trifluoromethyl)acetylene and (diethoxyphosphoryl)acetylene, activated by the presence of strongly electron-withdrawing substituents, were also unsuccessful. Some of the thiopyran derivatives 4 and 5 obtained in

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

• the PAE 10b with an additional acetylene fragment differed from the absorption spectrum of the PAE 10a by a small bathochromic shift (≈7 nm) of two absorption bands and an additional absorption band at 266 nm (Figure 6). The fluorescence emission spectra of the same solutions (Figure 7) were recorded

2-(1-Hydroxypropyn-2-yl)-1-vinylpyrroles: the first successful Favorsky ethynylation of pyrrolecarbaldehydes

• A. V. Ivanov,
• V. S. Shcherbakova,
• I. A. Ushakov,
• L. N. Sobenina,
• O. V. Petrova,
• A. I. Mikhaleva and
• B. A. Trofimov

Beilstein J. Org. Chem. 2015, 11, 228–232, doi:10.3762/bjoc.11.25

• .11.25 Abstract 1-Vinylpyrrole-2-carbaldehydes react with acetylene at atmospheric pressure in a NaOH/EtOH/DMSO system at 7–10 °C to afford 2-(1-hydroxypropyn-2-yl)-1-vinylpyrroles in 53–94% yield. Thus, the first base-mediated direct ethynylation of pyrrolecarbaldehydes with free acetylene under

• modified conditions of the Favorsky reaction has been implemented to pave an expedient route to important biomolecules containing a pyrrole ring. Keywords: acetylene; ethynylation; Favorsky reaction; 1-vinylpyrrole-2-carbaldehyde; Introduction Functionalized pyrroles bearing a terminal acetylenic moiety

• pyrrole-2-carbaldehyde with acetylene under conditions, well suited for the synthesis of secondary acetylenic alcohols (KOH/H2O/DMSO, atmospheric pressure, −5 to −7 °C) from aromatic and heteroaromatic aldehydes [9], appeared to be unsuccessful: the starting aldehyde was almost quantitatively recovered

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• -acyliminium ion cyclisation strategy in the presence of a disubstituted acetylene nucleophile. Anodic oxidation proceeded in high yield and a smooth cyclisation of the pendant acetylene nucleophile was triggered by treatment with titanium tetrachloride. Ozonolysis of the chloromethyl alkene intermediate

One-pot functionalisation of N-substituted tetrahydroisoquinolines by photooxidation and tunable organometallic trapping of iminium intermediates

• Joshua P. Barham,
• Matthew P. John and
• John A. Murphy

Beilstein J. Org. Chem. 2014, 10, 2981–2988, doi:10.3762/bjoc.10.316

• of methopholine (3, Scheme 2). Previous syntheses of 3 involving oxidative functionalisation of 16a have used (4-chlorophenyl)acetylene as a pronucleophile [13][46]. However, isolation and hydrogenation of the resulting THIQ intermediate are required to access 3. Photoactivation of 16a and trapping

Mono- and multilayers of molecular spoked carbazole wheels on graphite

• Stefan-S. Jester,
• A. Vikas Aggarwal,
• Daniel Kalle and
• Sigurd Höger

Beilstein J. Org. Chem. 2014, 10, 2783–2788, doi:10.3762/bjoc.10.295

• curved (or bent; as seen in the molecular model in Figure 2c and d where one of the six carbazole units is marked by a white arrow). They are still not directly connected, but terminated with acetylene units. However, a gap can rarely be estimated from the brightness modulation (cf. circle in Figure 2c

Self-assembled monolayers of shape-persistent macrocycles on graphite: interior design and conformational polymorphism

• Joscha Vollmeyer,
• Friederike Eberhagen,
• Sigurd Höger and
• Stefan-S. Jester

Beilstein J. Org. Chem. 2014, 10, 2774–2782, doi:10.3762/bjoc.10.294

• Joscha Vollmeyer Friederike Eberhagen Sigurd Hoger Stefan-S. Jester Kekulé-Institut für Organische Chemie und Biochemie, Rheinische Friedrich-Wilhelms-Universität Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany 10.3762/bjoc.10.294 Abstract Three shape-persistent naphthylene–phenylene–acetylene

A general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes

• Shekaraiah Devari,
• Manjeet Kumar,
• Ramesh Deshidi,
• Masood Rizvi and
• Bhahwal Ali Shah

Beilstein J. Org. Chem. 2014, 10, 2649–2653, doi:10.3762/bjoc.10.277

• forming an oxonium ion intermediate, which is attacked by trimethylsilylacetylene to give the corresponding product (Scheme 3, reaction 2). The stereochemistry of the reaction products is possibly determined by the coordination between two π-electron orbitals of the oxocarbonium ion and the acetylene

Selenium halide-induced bridge formation in [2.2]paracyclophanes

• Laura G. Sarbu,
• Henning Hopf,
• Peter G. Jones and
• Lucian M. Birsa

Beilstein J. Org. Chem. 2014, 10, 2550–2555, doi:10.3762/bjoc.10.266

• Analytical Chemistry, Technical University of Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany 10.3762/bjoc.10.266 Abstract An addition/elimination sequence of selenium halides to pseudo-geminally bis(acetylene) substituted [2.2]paracyclophanes leads to new bridges with an endo-exo-diene

• intramolecular photocyclization, yielding the corresponding ladderane isomers [9][10][11]. The ethynyl group is well known for its ability to undergo coupling reactions, making the pseudo-geminal bis(acetylene) 1 and its derivatives good candidates for building molecular scaffolding [12][13]. The reaction

• between bis(acetylene) 1 and other acetylene derivatives has been reported to provide new π-bridges in [2.2]paracyclophane [14]. Furthermore, a new way for bridging [2.2]paracyclophanes has been accomplished by the addition of selenium monochloride to pseudo-geminally substituted bis(propargylic) alcohols

Building complex carbon skeletons with ethynyl[2.2]paracyclophanes

• Ina Dix,
• Lidija Bondarenko,
• Peter G. Jones,
• Thomas Oeser and
• Henning Hopf

Beilstein J. Org. Chem. 2014, 10, 2013–2020, doi:10.3762/bjoc.10.209

• yield (67%; for the spectroscopic data see Supporting Information File 1). In this intermediate the three triple bonds to be converted into a benzene ring possess only one degree of freedom: the rotation of the non-phane benzene ring around its connecting acetylene group. The cyclotrimerization of three

Microwave-assisted Cu(I)-catalyzed, three-component synthesis of 2-(4-((1-phenyl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)-1H-benzo[d]imidazoles

• Yogesh Kumar,
• Vijay Bahadur,
• Anil K. Singh,
• Virinder S. Parmar,
• Erik V. Van der Eycken and
• Brajendra K. Singh

Beilstein J. Org. Chem. 2014, 10, 1413–1420, doi:10.3762/bjoc.10.145

• , when path A and path B were explored, the desired product was afforded in different yields (Scheme 1). The treatment of acetylene 2a with phenylazide (1a) in the presence of copper sulfate and D-glucose as a reductant [32][33] in THF/H2O (2:1) as a solvent under stirring at rt as well as under

An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

• Quanxuan Zhang,
• Hong Ren and
• Gregory L. Baker

Beilstein J. Org. Chem. 2014, 10, 1365–1371, doi:10.3762/bjoc.10.139

• polymerization of functional lactide monomers, post-polymerization modification, or a combination of these two approaches. The appending hydroxy [9], carboxyl [10], poly(ethylene glycol) (PEG) [11][12][13][14], allyl [15], azido [16] and acetylene [17] functionalities on PLA backbones have been reported and

• offered great opportunities for covalent post-polymerization modification of PLAs. Among various functional groups, acetylene functionalized PLA has attracted much attention [17][18][19]. By having a single functional lactide monomer, it allows for facile placement of a broad range of pendant functional

• because of its high selectivity and excellent tolerance to different functional groups and reaction conditions. Our group has prepared the first ‘clickable’ PLA using 2-hydroxy-4-pentynoic acid (1) as a precursor (Scheme 1) and studied ‘click’ modification of acetylene functionalized PLA [17]. One new

Synthesis, characterization and DNA interaction studies of new triptycene derivatives

• Sourav Chakraborty,
• Snehasish Mondal,
• Rina Kumari,
• Sourav Bhowmick,
• Prolay Das and
• Neeladri Das

Beilstein J. Org. Chem. 2014, 10, 1290–1298, doi:10.3762/bjoc.10.130

• tribromotriptycenes as synthons [36], syntheses of triethynyltriptycenes (TETs) 1 and 2 were efficiently realized in two steps (Scheme 1). In the presence of Pd(0) catalyst and cuprous iodide (cocatalyst), Sonogashira cross-coupling reaction of 2,6,14-tribromotriptycene with 3.0 equiv of (trimethylsilyl)acetylene in

Tandem Cu-catalyzed ketenimine formation and intramolecular nucleophile capture: Synthesis of 1,2-dihydro-2-iminoquinolines from 1-(o-acetamidophenyl)propargyl alcohols

• Gadi Ranjith Kumar,
• Yalla Kiran Kumar,
• Ruchir Kant and
• Maddi Sridhar Reddy

Beilstein J. Org. Chem. 2014, 10, 1255–1260, doi:10.3762/bjoc.10.125

• , the reaction is not possible with acetylene as the alkyne partner to produce 3,4-unsubstituted adducts. We herein report the intramolecular version of Wang's protocol for the synthesis of differently substituted products. To explore the practicality of the above reaction, a series of starting