Gold(I)-catalyzed formation of furans from γ-acyloxyalkynyl ketones

• Marie Hoffmann,
• Solène Miaskiewicz,
• Jean-Marc Weibel,
• Patrick Pale and
• Aurélien Blanc

Beilstein J. Org. Chem. 2013, 9, 1774–1780, doi:10.3762/bjoc.9.206

• -acyloxyalkynyl ketones were efficiently converted into highly substituted furans with 2.5 mol % of triflimide (triphenylphosphine)gold(I) as a catalyst in dichloroethane at 70 °C. Keywords: alkynyl ketones; cycloisomerization; furans; gold-catalysis; 1,2-migration; Introduction Furans are an important class of

• Gagosz’s catalyst [54], i.e. (triphenylphosphine)gold(I) triflimide, in dichloroethane at room temperature. In both cases, a fast consumption of the starting material 1a was observed compared to the copper(I) catalysis, but lower yields of furans, 44% and 65% respectively, were obtained mostly due to the

Gold-catalyzed cyclization of allenyl acetal derivatives

• Dhananjayan Vasu,
• Samir Kundlik Pawar and
• Rai-Shung Liu

Beilstein J. Org. Chem. 2013, 9, 1751–1756, doi:10.3762/bjoc.9.202

• . Experimental General procedure for the gold-catalyzed carbocyclization General procedure for the the gold(I)-catalyzed carbocyclization of vinylallenyl acetal: A two-necked flask was charged with chloro(triphenylphosphine)gold(I) (11.1 mg, 0.022 mmol) and silver triflate (5.8 mg, 0.022 mmol), and to this

• propargylic ester acetals: Chloro(triphenylphosphine)gold(I) (8.0 mg, 0.016 mmol) and silver triflate (4.2 mg, 0.016 mmol) were added to a dried Schlenk tube under an N2 atmosphere, and freshly distilled CH2Cl2 (1.0 mL) was introduced by a syringe. The resulting mixture was stirred at room temperature for 10

The preparation of several 1,2,3,4,5-functionalized cyclopentane derivatives

• André S. Kelch,
• Peter G. Jones,
• Ina Dix and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 1705–1712, doi:10.3762/bjoc.9.195

• failed so far, as is also shown in Scheme 3. Only in one case was a halogenated derivative obtained in poor yield: treatment of 16 with triphenylphosphine–bromine in carbon tetrachloride provided the tribromo ether derivative 19 as a minor component. Surprisingly, this had the cis,cis,cis,trans

• solvents). However, with the triphenylphosphine–bromine complex, a mixture of the pentabromides 29 was obtained in very good yield (73%). The superior results in comparison with 16 probably can be rationalized by a decreased steric shielding of the hydroxymethyl groups in 30, but are probably also

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

• Ping-An Wang

Beilstein J. Org. Chem. 2013, 9, 1677–1695, doi:10.3762/bjoc.9.192

• catalytic amounts of tetra-n-butylammonium chloride or triphenylphosphine to afford trans O-protected vicinal chlorohydrins in quantitative yields. This pioneering work opened the possibility for desymmetrization of meso-epoxides by small organic molecules, but the exploration of organocatalysts for the

Bromination of hydrocarbons with CBr₄, initiated by light-emitting diode irradiation

• Yuta Nishina,
• Bunsho Ohtani and
• Kotaro Kikushima

Beilstein J. Org. Chem. 2013, 9, 1663–1667, doi:10.3762/bjoc.9.190

• useful bromide-containing precursors. For instance, alkyl alcohols can be converted to alkyl bromides in the presence of CBr4 and triphenylphosphine; this is known as the Appel reaction [28]. This combination can also be used to transform aldehydes into dibromoalkenes, which are useful precursors for the

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

• coordinating agents, such as triethylamine and triphenylphosphine, clearly retard the process. Therefore, a dissociative mechanism has been proposed to generate the unsaturated species 31. Then, one methyl group of the coordinated tmtu can stabilize the open coordination site via agostic interaction, 32

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

• Todd J. Eckroat,
• Abdelrahman S. Mayhoub and
• Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

Appel-reagent-mediated transformation of glycosyl hemiacetal derivatives into thioglycosides and glycosyl thiols

• Tamashree Ghosh,
• Abhishek Santra and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 974–982, doi:10.3762/bjoc.9.112

• thiols in a one-pot two-step reaction sequence mediated by Appel reagent (carbon tetrabromide and triphenylphosphine). 1,2-trans-Thioglycosides and β-glycosyl thiol derivatives were stereoselectively formed by the reaction of the in situ generated glycosyl bromides with thiols and sodium

• carbonotrithioate. The reaction conditions are reasonably simple and yields were very good. Keywords: Appel reagent; carbon tetrabromide; glycosyl hemiacetal; glycosyl thiol; thioglycoside; triphenylphosphine; Introduction Thioglycosides (1-thiosugar) are widely used glycosyl donors in glycosylation reactions [1

• agents (triphenylphosphine or combination of triethylsilane and BF3·OEt2) followed by the reaction of the in situ generated thiolate ions with glycosyl bromides under phase-transfer conditions [23] or in ionic liquids [24]; (b) reaction of glycosyl bromides with thiols under phase-transfer conditions [25

Synthesis of skeletally diverse alkaloid-like molecules: exploitation of metathesis substrates assembled from triplets of building blocks

• Sushil K. Maurya,
• Mark Dow,
• Stuart Warriner and
• Adam Nelson

Beilstein J. Org. Chem. 2013, 9, 775–785, doi:10.3762/bjoc.9.88

• propagating building block, DEAD and triphenylphosphine was used. In general, the crude product was directly deacetylated. At each stage, the required fluorous-tagged product was isolated by fluorous-solid-phase extraction (F-SPE), and its purity determined by analysis by 500 MHz 1H NMR spectroscopy. These

• results are summarised in Table 1. The metathesis substrates were prepared by subsequent attachment of a terminating building block (12a, 12b or 13) (see Table 2). In each case, an excess of the terminating building block, DEAD and triphenylphosphine was used; the required fluorous-tagged product was

Synthesis and structure of trans-bis(1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene)palladium(II) dichloride and diacetate. Suzuki–Miyaura coupling of polybromoarenes with high catalytic turnover efficiencies

• Jeelani Basha Shaik,
• Venkatachalam Ramkumar,
• Babu Varghese and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2013, 9, 698–704, doi:10.3762/bjoc.9.79

• %), triphenylphosphine (4 mg, 4 mol %), NaOH (62 mg, 1.54 mmol, 8 equiv) was heated under reflux in 4 mL of 1,4-dioxane under nitrogen atmosphere. The reaction was completed in 8 h (monitored by TLC). The reaction mixture was diluted with water (10 mL) and extracted with CH2Cl2 (3 × 5 mL). The organic layer was dried

Facile synthesis of benzothiadiazine 1,1-dioxides, a precursor of RSV inhibitors, by tandem amidation/intramolecular aza-Wittig reaction

• Krishna C. Majumdar and
• Sintu Ganai

Beilstein J. Org. Chem. 2013, 9, 503–509, doi:10.3762/bjoc.9.54

• synthesis of a benzothiadiazine 1,1-dioxide derivative using substrate 9b by intramolecular aza-Wittig reaction. To test this premise, 9b was treated with triphenylphosphine in THF at room temperature, but no desired product was obtained, and only the intermediate iminophosphorane 12b was isolated, even

• -boiling-point solvent, i.e., o-dichlorobenzene (DCB). The reaction was successful at higher temperature, affording the desired cyclized product 13b (54%) along with the by-product triphenylphosphine oxide (Table 1, entry 5). Subsequently, we turned our attention to develop a simpler one-step procedure by

A new synthetic protocol for coumarin amino acid

• Xinyi Xu,
• Xiaosong Hu and
• Jiangyun Wang

Beilstein J. Org. Chem. 2013, 9, 254–259, doi:10.3762/bjoc.9.30

• –Wadsworth–Emmons reaction has a significant advantage: The resulting phosphate byproduct can be readily separated, whereas the byproduct triphenylphosphine oxide generated in the Wittig reaction is difficult to remove [17]. The effect of the base used in the Horner–Wadsworth–Emmons reaction on the reaction

Alkyne hydroarylation with Au N-heterocyclic carbene catalysts

• Cristina Tubaro,
• Marco Baron,
• Andrea Biffis and
• Marino Basato

Beilstein J. Org. Chem. 2013, 9, 246–253, doi:10.3762/bjoc.9.29

• than the corresponding triphenylphosphine complexes. Finally, tests performed on the intramolecular hydroarylation of substrates 5{1} and 5{2} indicate that the reaction does not take place under neutral conditions, whereas under acidic conditions products of alkyne hydration by traces of water present

Asymmetric synthesis of host-directed inhibitors of myxoviruses

• Terry W. Moore,
• Kasinath Sana,
• Dan Yan,
• Pahk Thepchatri,
• John M. Ndungu,
• Manohar T. Saindane,
• Mark A. Lockwood,
• Michael G. Natchus,
• Dennis C. Liotta,
• Richard K. Plemper,
• James P. Snyder and
• Aiming Sun

Beilstein J. Org. Chem. 2013, 9, 197–203, doi:10.3762/bjoc.9.23

• -methylaniline (16) [17] (Scheme 4b)) in the presence of a slight excess of triphenylphosphine and diethyl azodicarboxylate, we acquired the desired products 14 in good yield and ee. This methodology is attractive because of the high ee that can be obtained from the inexpensive and readily available (L)-lactic

Alkenes from β-lithiooxyphosphonium ylides generated by trapping α-lithiated terminal epoxides with triphenylphosphine

• David. M. Hodgson and
• Rosanne S. D. Persaud

Beilstein J. Org. Chem. 2012, 8, 1896–1900, doi:10.3762/bjoc.8.219

A quantitative approach to nucleophilic organocatalysis

• Herbert Mayr,
• Sami Lakhdar,
• Biplab Maji and
• Armin R. Ofial

Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166

• comparison reveals that the nucleophilicities of the NHCs 41–43 do not differ fundamentally from those of other organocatalysts, e.g., triphenylphosphine (10b), DMAP (39), and DABCO (38) [96]. The considerably lower nucleophilicity of the triazolylidene 43 compared with the imidazolylidene 42 can be

A novel asymmetric synthesis of cinacalcet hydrochloride

• Veera R. Arava,
• Laxminarasimhulu Gorentla and
• Pramod K. Dubey

Beilstein J. Org. Chem. 2012, 8, 1366–1373, doi:10.3762/bjoc.8.158

• simply by heating 12 in 48% aqueous HBr solution under reflux for 15 h. The obtained crude was purified by passing it through a silica gel plug with n-hexane to afford 5 in 82% yield. Iodide 6 was prepared by reacting 12 with molecular iodine in the presence of triphenylphosphine and imidazole in CH2Cl2

• ); 13C NMR (CDCl3/TMS) δ 141.36, 131.87, 130.67 (q, CF3), 128.83, 125.07, 123.03, 33.70, 33.67, 32.52. Preparation of 1-(3-iodopropyl)-3-trifluoromethylbenzene (6): Compound 12 (50.0 g, 0.244 mol) was dissolved in CH2Cl2 (150.0 mL) and imidazole (2.0 g, 0.029 mol) and triphenylphosphine (70.64 g, 0.269

Synthesis of a novel chemotype via sequential metal-catalyzed cycloisomerizations

• Bo Leng,
• Stephanie Chichetti,
• Shun Su,
• Aaron B. Beeler and
• John A. Porco Jr.

Beilstein J. Org. Chem. 2012, 8, 1338–1343, doi:10.3762/bjoc.8.153

• synthesis of alkynyl o-benzaldehydes: 2-(3-(but-2-ynyloxy)prop-1-ynyl)benzaldehyde. To a solution of 2-bromobenzaldehyde (2.0 g, 10.8 mmol) and 1-(prop-2-ynyloxy)but-2-yne (1.4 g, 13 mmol) in Et3N (68 mL), was added tetrakis(triphenylphosphine)palladium(0) (0.38 g, 0.32 mmol). The reaction mixture was

Synthesis of diverse indole libraries on polystyrene resin – Scope and limitations of an organometallic reaction on solid supports

• Kerstin Knepper,
• Sylvia Vanderheiden and
• Stefan Bräse

Beilstein J. Org. Chem. 2012, 8, 1191–1199, doi:10.3762/bjoc.8.132

• calculated as if complete conversion had taken place. GP 3 - Suzuki reaction: Under an argon atmosphere, one equiv of the respective 7-bromo-1H-indole-6-carboxymethyl-polystyrene is suspended in DMF (0.1 mmol/mL) together with 0.10 equiv of tetrakis(triphenylphosphine)palladium and two equiv of boronic acid

• 10.0 mol % bis(triphenylphosphine)palladium(II) chloride, 15.0 mol % copper(I) iodide and one equiv of triphenylphosphine. Then, two equiv of triethylamine and 2.5 equiv of 4-ethynylanisole are added and the mixture is agitated for two days at 80 °C. After cooling down to room temperature, 10 mL of a

• , one equiv of the respective 7-bromo-1H-indole-6-carboxymethyl-polystyrene is suspended in DMF (0.1 mmol/mL) together with 10.0 mol % bis(triphenylphosphine)palladium(II) chloride, 15.0 equiv of lithium chloride and one equiv of triphenylphosphine. Then, three equiv of tributyl(vinyl)tin are added and

Parallel solid-phase synthesis of diaryltriazoles

• Matthias Wrobel,
• Jeffrey Aubé and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 1027–1036, doi:10.3762/bjoc.8.115

• of regioisomers in reaction 3. Instead of the 1,4-disubstituted triazoles obtained from copper(I) catalysis, the complex pentamethylcyclopentadienylbis(triphenylphosphine)ruthenium(II) chloride leads to 1,5-disubstituted triazole compounds [19]. 4-(Azidomethyl)benzoic acid functionalized Wang resin 7

• preliminary work, resin 7 was therefore reacted with internal alkynes 14a–c and pentamethylcyclopentadienylbis(triphenylphosphine)ruthenium(II) chloride as catalyst in DMF at 70 °C overnight followed by TFA cleavage [20]. LC–MS analysis of the crude product revealed the formation of compounds 15a–c in high

• ) was preswollen in dimethylformamide (2 mL/100 mg resin) for 2 h at room temperature. Subsequently, the catalyst complex pentamethylcyclopentadienylbis(triphenylphosphine)ruthenium(II) chloride, Cp·RuCl(PPh3)2, (5 mol %) and either a terminal or an internal alkyne (4 equiv) were added. After the

Toward unidirectional switches: 2-(2-Hydroxyphenyl)pyridine and 2-(2-methoxyphenyl)pyridine derivatives as pH-triggered pivots

• Christina Tepper and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2012, 8, 977–985, doi:10.3762/bjoc.8.110

• the bipyridine 9 with 2-methoxyphenylboronic acid or 2-hydroxyphenylboronic acid, respectively, using tetrakis(triphenylphosphine)palladium(0) and potassium carbonate as a base in dioxane. In the resulting switches 10 and 13 the more stable diastereomeric conformations should be those in which the

• absorption spectra were recorded with a Jasco J-815 spectrophotometer. 2-(2-Methoxyphenyl)-3-methylpyridine (7): To a solution of 2-bromo-3-methylpyridine (184 mg, 1.07 mmol), 2-methoxyphenylboronic acid (151 mg, 0.99 mmol) and tetrakis(triphenylphosphine)palladium(0) (45 mg, 3.9 mol %) in dioxane (10 mL), a

• , 184.0768; found, 184.0815. Methoxyphenylpyridine switch (10): To a solution of dibromide 9 (20 mg, 0.022 mmol) and tetrakis(triphenylphosphine)palladium(0) (1 mg, 3.9 mol%) in dioxane (3 mL), a saturated potassium carbonate solution (0.2 mL) was added. The mixture was purged with argon for 10 min and

Carbohydrate-auxiliary assisted preparation of enantiopure 1,2-oxazine derivatives and aminopolyols

• Marcin Jasiński,
• Dieter Lentz and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2012, 8, 662–674, doi:10.3762/bjoc.8.74

• by treatment with tetrabromomethane in the presence of triphenylphosphine gave no satisfactory results, possibly due to the formation of the corresponding oxirane and its diverse, subsequent reactions. Conclusion We achieved the efficient synthesis of enantiopure hydroxylated tetrahydro-2H-1,2

Liquid-crystalline nanoparticles: Hybrid design and mesophase structures

• Gareth L. Nealon,
• Romain Greget,
• Cristina Dominguez,
• Zsuzsanna T. Nagy,
• Daniel Guillon,
• Jean-Louis Gallani and
• Bertrand Donnio

Beilstein J. Org. Chem. 2012, 8, 349–370, doi:10.3762/bjoc.8.39

• nm diameter were first synthesised and isolated with a triphenylphosphine protective layer, followed by the addition of thiols 68–12 (Figure 3). The authors estimated the number of ligands attached to the NPs after the exchange process to be ~150–215, which indicated a very dense packing on the

Improved syntheses of high hole mobility phthalocyanines: A case of steric assistance in the cyclo-oligomerisation of phthalonitriles

• Daniel J. Tate,
• Rémi Anémian,
• Richard J. Bushby,
• Suwat Nanan,
• Stuart L. Warriner and
• and Benjamin J. Whitaker

Beilstein J. Org. Chem. 2012, 8, 120–128, doi:10.3762/bjoc.8.14

• flame-dried flask purged with argon was added triphenylphosphine (44.61 g, 0.170 mol), imidazole (16.16 g, 0.255 mol) and anhydrous diethyl ether/acetonitrile (125 mL/125 mL). The stirred reaction mixture was cooled (0 °C, ice bath) and 3-methylbutanol (7.50 g, 0.085 mol) was added. After 10 min, iodine

• -methylbutyl)phthalonitrile (6e) To a flame-dried flask, under an argon atmosphere, were added bis(triphenylphosphine)nickel(II) dichloride (1.18 g, 1.82 mmol), triphenylphosphine (0.95 g, 3.6 mmol) and anhydrous THF (40 mL). n-Butyllithium (1.45 mL, 3.64 mmol, 2.5 M in hexanes) was added to the stirred

• triphenylphosphine was extracted. The title compound [24] was isolated as colourless needles (3.51 g, 72%) by increasing the polarity to 10% EtOAc/hexane (v:v). Rf ~ 0.30; mp (petroleum ether) 62–63 °C; IR (neat): 2957 (C–H), 2936 (C–H), 2872 (C–H), 2226 (CN), 1468 (C=C), 1459 (C=C) cm−1; 1H NMR (CDCl3, 500 MHz) δ

Binding of group 15 and group 16 oxides by a concave host containing an isophthalamide unit

• Jens Eckelmann,
• Vittorio Saggiomo,
• Svenja Fischmann and
• Ulrich Lüning

Beilstein J. Org. Chem. 2012, 8, 11–17, doi:10.3762/bjoc.8.2

• sulfoxides were chosen as guests, namely pyridine-N-oxide (PyNO) [18][19] and triphenylphosphine oxide (TPPO). PyNO showed the same behaviour as DMSO, i.e., large CIS for concave host 1, and small CIS for the linear compound (Figure 2, PyNO, endo-CH, 0.34 ppm for 1 and 0.14 ppm for 2). In contrast, with TPPO

• and its non-macrocyclic model 2. Expansion of a part of the 1H NMR spectra (200 MHz, 298 K) of pure 1 and 2 in CD2Cl2 (bottom) and after addition of TBACl, DMSO, pyridine-N-oxide (PyNO), triphenylphosphine oxide (TPPO), from bottom to top, respectively. NH proton (red circles), endo-CH proton (red