Thiophene-based donor–acceptor co-oligomers by copper-catalyzed 1,3-dipolar cycloaddition

• Stefanie Potratz,
• Amaresh Mishra and
• Peter Bäuerle

Beilstein J. Org. Chem. 2012, 8, 683–692, doi:10.3762/bjoc.8.76

• )-[2,2':3',2''terthiophene] and 2-[5,5"-bis(trimethylsilyl)-[2,2':3',2"-terthien]-5'-yl]ethynyl-1-trimethylsilane were synthesized according to the literature [44]. 3-Azidothiophene (2): In a mixture of ethanol (2.8 mL) and water (1.2 mL) 3-iodothiophene (1, 0.22 mL, 2 mmol), copper(I) iodide (38 mg, 0.2

• , 51.58; H, 3.11; N, 17.98; S, 27.73; CIMS m/z: (M + H) 234, (M − N2) 206, (M − C4H3N2S) 122. 4-(2,2'-Bithien-5-yl)-1-(thien-2-yl)-1H-1,2,3-triazole (12): 2-Iodothiophene (3, 0.11 mL, 1 mmol), 5-ethynyl-2,2'-bithiophene (190 mg, 1 mmol), sodium azide (130 mg, 2 mmol), copper(I) iodide (19 mg, 0.1 mmol

• , 128.05, 131.95, 135.89; CIMS m/z: (M+) 316, (M − N2) 288; HRMS–ESI (m/z): (M + Na) calcd for C14H9N3NaS3, 337.9851; found, 337.9847; (M + H) calcd for C14H10N3S3, 316.0031; found, 316.0026. 1,4-Di(2,2'-bithien-5-yl)-1H-1,2,3-triazole (14): 5-Iodo-2,2'-bithiophene (0.92 g, 1 mmol), 5-ethynyl-2,2

Synthesis of multivalent host and guest molecules for the construction of multithreaded diamide pseudorotaxanes

• Nora L. Löw,
• Egor V. Dzyuba,
• Boris Brusilowskij,
• Lena Kaufmann,
• Elisa Franzmann,
• Wolfgang Maison,
• Emily Brandt,
• Daniel Aicher,
• Arno Wiehe and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2012, 8, 234–245, doi:10.3762/bjoc.8.24

• reactions. Therefore, ethynyl-substituted benzene spacers 9, 11 and 13 were used to synthesize a bent divalent (10), a linear divalent (12), and a trivalent wheel (14) [103] (Scheme 2 and Scheme 3). From the enormously broad choice of different Pd-catalysts and reaction conditions, we used (Ph3P)2PdCl2 and

• " of multivalent host and guest molecules has been described, which can be obtained from the two easy-to-prepare building blocks 1 and 2 by Sonogashira coupling reactions to ethynyl-substituted spacers. This synthetic approach is convergent, and thus the sometimes limited yields do not detract from

Highly efficient cyclosarin degradation mediated by a β-cyclodextrin derivative containing an oxime-derived substituent

• Michael Zengerle,
• Florian Brandhuber,
• Christian Schneider,
• Franz Worek,
• Georg Reiter and
• Stefan Kubik

Beilstein J. Org. Chem. 2011, 7, 1543–1554, doi:10.3762/bjoc.7.182

• , DMF/toluene, 3 h, 25 °C, 39%. Syntheses of 6-ethynyl-formylpyridine oximes (7a–c). Reagents and conditions: i. CuI, (PPh3)2PdCl2, DPEphos, NEt3, 18–20 h, 25 °C, 71-87%; ii. NH2OH, H2O, 30 min, 80 °C; iii. TBAF, THF, 1 h, 0 °C, 68–83%. Reaction conditions used for the preparation of cyclodextrin

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• -sulfonylindoles in good to high yields (Scheme 26). Nakamura and co-workers synthesized 3-mesyl-1-methyl-2-propylindole 147, 3-mesyl-1-methyl-2-phenylindole 148, and 3-mesyl-1-methylindole 149 from N-mesyl-N-methyl-2-(1-pentynyl)aniline, N-mesyl-N-methyl-2-(phenylethynyl)aniline, and 2-ethynyl-N-mesyl-N

Gold-catalyzed heterocyclizations in alkynyl- and allenyl-β-lactams

• Benito Alcaide and
• Pedro Almendros

Beilstein J. Org. Chem. 2011, 7, 622–630, doi:10.3762/bjoc.7.73

• substituents at the C–C double bond were tolerated, including benzyloxyethyl and cyclohexyl (geminal to the ethynyl group) as well as hexyl and phenyl (vicinal to the lactam), and gave dihydroindolizinones with different substituents at their 1- and 2-positions. Substrates with the C–C double bond embedded in

One-pot gold-catalyzed synthesis of 3-silylethynyl indoles from unprotected o-alkynylanilines

• Jonathan P. Brand,
• Clara Chevalley and
• Jérôme Waser

Beilstein J. Org. Chem. 2011, 7, 565–569, doi:10.3762/bjoc.7.65

• conditions. We recently reported a mild procedure for the C3-selective alkynylation of indoles using AuCl and the commercially available benziodoxolone TIPS-EBX (1-[(triisopropylsilyl)ethynyl]-1,2-benziodoxol-3(1H)-one (1)) (Scheme 2) [35][36][37][38][39][40]. This methodology allowed the ethynylation of a

Synthesis of 5-(2-methoxy-1-naphthyl)- and 5-[2-(methoxymethyl)-1-naphthyl]-11H-benzo[b]fluorene as 2,2'-disubstituted 1,1'-binaphthyls via benzannulated enyne–allenes

• Yu-Hsuan Wang,
• Joshua F. Bailey,
• Jeffrey L. Petersen and
• Kung K. Wang

Beilstein J. Org. Chem. 2011, 7, 496–502, doi:10.3762/bjoc.7.58

• -naphthyl derivatives. Construction of a new 1-naphthyl ring as an essential step toward 1,1'-binaphthyls is rare [17][18][19]. Results and Discussion The Sonogashira reaction between 1-ethynyl-2-methoxybenzene (4a) and 1-iodo-2-[2-(trimethylsilyl)ethynyl]benzene produced 5a, which was desilylated to give

• -ethynyl-2-(methoxymethyl)benzene (4b). On exposure to potassium tert-butoxide in refluxing toluene for five hours, 9a was transformed to 5-(2-methoxyphenyl)-11H-benzo[b]fluorene 13a along with a small amount (ca. 2%) of 14a in a single operation. Presumably, the cascade sequence involved an initial 1,3

• nitrogen atmosphere. Diethyl ether and tetrahydrofuran (THF) were distilled from benzophenone ketyl prior to use. 1-Ethynyl-2-methoxybenzene (4a), pivalophenone (7), n-butyllithium (1.6 M) in hexanes, 1-bromo-2-[2-(trimethylsilyl)ethynyl]benzene, triethylsilane, trifluoroacetic acid, potassium tert

A rapid and efficient synthetic route to terminal arylacetylenes by tetrabutylammonium hydroxide- and methanol-catalyzed cleavage of 4-aryl-2-methyl-3-butyn-2-ols

• Jie Li and
• Pengcheng Huang

Beilstein J. Org. Chem. 2011, 7, 426–431, doi:10.3762/bjoc.7.55

• promise for the preparation of arylacetylenes with multiple terminal ethynyl groups such as dendritic macromolecules, which will broaden the application of the low-cost reagent 2-methyl-3-butyn-2-ol in the preparation of arylacetylenes. Experimental General procedure for the deprotection reaction using

Oxidative allylic rearrangement of cycloalkenols: Formal total synthesis of enantiomerically pure trisporic acid B

• Silke Dubberke,
• Muhammad Abbas and
• Bernhard Westermann

Beilstein J. Org. Chem. 2011, 7, 421–425, doi:10.3762/bjoc.7.54

• cyclohexenone (+)-7, which is the key building block in our synthesis, was the incorporation of a C2 unit into β-ketoester (−)-1c (Scheme 3). This was achieved by adding ethynyl magnesium bromide in THF at room temperature. The cyclohexenol (+)-6 can be isolated in 79% yield with a diastereomeric ratio of 96:4

• (s), 134.9 (s, =C-), 144.5 (d, =CH), 173.6 (s, CO), 197.6 (s, CO); GC–MS (80 eV) m/z (%): 182 (25), 167 (28), 150 (50), 135 (15), 123 (41), 95 (22), 82 (100), 79 (14); Anal. Calcd for C10H14O3 (182.2): C, 65.92; H, 7.74. Found: C, 65.78; H, 7.75. Methyl (+)-(1R,2R*)-2-ethynyl-2-hydroxy-1,3

• -dimethylcyclohex-3-ene-1-carboxylate (6). To a solution of (−)-1c (0.50 g, 2.75 mmol) in THF (5 mL), was added dropwise over a period of 30 min ethynyl magnesium bromide (0.5 M in THF; 9.05 mL, 4.53 mmol) at 20 °C. Stirring at this temperature was continued for 1 h, and then the reaction mixture was quenched by

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• into the visible region. The most commonly employed strategy for the bathochromic shifting of the emission wavelength is to extend the conjugation of the fluorophores with aryl, ethenyl and ethynyl groups. The addition of electron donating and withdrawing substituents to these conjugation enhancing

• reports on the extension of conjugation of the triphenylene chromophore have appeared. 2,3,6,7,10,11-Hexakis(ethynyl)triphenylene derivatives have been used in photonics as organic light emitting diode (OLED) materials [40][41][42]. Therefore, it is worthwhile to tune the fluorescence emission of the

Recent advances in carbocupration of α-heterosubstituted alkynes

• Ahmad Basheer and
• Ilan Marek

Beilstein J. Org. Chem. 2010, 6, No. 77, doi:10.3762/bjoc.6.77

• the organocopper by the oxygen of the THP completely reversed the regiochemistry of the carbocupration reaction [8]. Ethynyl carbamate is also an oxy-substituted acetylene (and therefore should lead to the branched product). However, the electron-withdrawing group properties of the carbamoyl group

• 80/20, Scheme 7). Copper-catalyzed carbomagnesiation could even further increase the efficiency of these reactions. Thus, when ethynyl carbamate 12a was added to a stoichiometric amount of alkylmagnesium halide in Et2O in the presence of 10 mol % CuI, the corresponding (E)-substituted alkene was

Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

• Dhananjaya Sahoo,
• Susanne Thiele,
• Miriam Schulte,
• Navid Ramezanian and
• Adelheid Godt

Beilstein J. Org. Chem. 2010, 6, No. 57, doi:10.3762/bjoc.6.57

• the oxidation product of 1a1, aldehyde 8a1, reacts with KOH to give the ethynyl anion and formic acid which immediately exchange a proton providing deprotected alkyne 21, the oxidation product of 5a, aldehyde 6a, is inert under the reaction conditions [69][70]. This finding is attributed to the higher

• energy content and therefore lower nucleofugicity of a vinyl anion as compared to an ethynyl anion. The products, alkyne 21 and the oxidized carbometalation product 6a, are easily separable by chromatography, which resembles a simple filtration through silica gel because 6a stays anchored on the solid

• and 5a with n-Bu4NF will not only remove the TIPS group of 1a1 but also the two TIPS groups of 5a (Scheme 3). The two products are as difficult to separate as the starting compounds. Furthermore, the ethynyl groups of both products are expected to have the same reactivity which can make the isolation

Preparation of pyridine-3,4-diols, their crystal packing and their use as precursors for palladium-catalyzed cross-coupling reactions

• Tilman Lechel,
• Irene Brüdgam and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, No. 42, doi:10.3762/bjoc.6.42

• dried over Na2SO4 and concentrated to dryness. The residue was purified by column chromatography on silica gel (hexane) followed by HPLC to give 98 mg (35%) of 4a as a colorless oil (volatile under high vacuum). 2-tert-Butyl-6-(trifluoromethyl)-3,4-bis[(triisopropylsilyl)ethynyl] pyridine (4a): 1H NMR

Synthetic incorporation of Nile Blue into DNA using 2′-deoxyriboside substitutes: Representative comparison of (R)- and (S)-aminopropanediol as an acyclic linker

• Daniel Lachmann,
• Sina Berndl,
• Otto S. Wolfbeis and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2010, 6, No. 13, doi:10.3762/bjoc.6.13

• evaluate the role of the chirality of the 3-amino-1,2-propanediol linker. Results and Discussion The DNA building block ethynyl (2R)-3-(4,4′-dimethoxytrityl)-2-[(2-cyanoethoxy)(diisopropylamino)phosphinooxy]propylcarbamate (3) contains the propargyl group attached to the glycol part by a carbamate function

Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules

• Matthias Lehmann and
• Jens Seltmann

Beilstein J. Org. Chem. 2009, 5, No. 73, doi:10.3762/bjoc.5.73

• iodobenzene 5 with ethynyl compound 4 and subsequent cleavage of the silyl protecting group afforded the arm derivatives 6. As in the previously published two-step synthesis, the arms 6 were linked successively to the non-symmetric thiadiazole bending unit 7 (Scheme 2) [24]. All compounds were carefully

Gold film- catalysed benzannulation by Microwave- Assisted, Continuous Flow Organic Synthesis (MACOS)

• Gjergji Shore,
• Michael Tsimerman and
• Michael G. Organ

Beilstein J. Org. Chem. 2009, 5, No. 35, doi:10.3762/bjoc.5.35

• , J = 4.5 Hz, 1H), 7.57 (m, 3H), 7.44 (t, J = 7.2 Hz, 1H), 7.41–7.37 (m, 3H). 13C NMR (75 MHz, CDCl3): δ 191.6, 135.8, 133.8, 133.2, 131.7, 129.1, 128.6, 128.5, 127.3, 126.9, 122.4, 96.4, 85.0. Spectra matched that found in the literature [37]. 2-[2-(Thiophen-3-yl)ethynyl]benzaldehyde (1d). Following

• ; H, 4.60. Spectra matched that found in the literature [38]. 3-Ethynyl-N,N-diisopropylbenzamide (2j). A 25 mL round-bottom flask was purged with argon, cooled to 0 °C, and 2.4 mL of dry THF and 157 μL (1.8 mmol) of oxalyl chloride were added. After 20 min., a cooled (0 °C) solution of 3-ethynyl

• : 276.1150; found 276.1153. [2-(Phenyl)naphthalen-1-yl](thiophen-3-yl)-methanone (3d). Following the general MACOS benzannulation protocol, 2-(2-(thiophen-3-yl)-ethynyl)-benzaldehyde (1d) and phenylacetylene were reacted and 650 μL of the crude reaction mixture were collected. Purification by flash

Tether- directed synthesis of highly substituted oxasilacycles via an intramolecular allylation employing allylsilanes

• Peter J. Jervis and
• Liam R. Cox

Beilstein J. Org. Chem. 2007, 3, No. 6, doi:10.1186/1860-5397-3-6

• substituents, such as n-Bu and TIPS-C≡C-groups, are employed (Entries 3,4, Table in Scheme 2) (A values:[17] ethynyl = 0.41–0.52 kcal mol-1; ethyl = 1.79 kcal mol-1). We acknowledge that analysing steric interactions and predicting favoured conformations for such heavily substituted six-membered cyclic T.S.s