The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

• Scheme 17). Starting with the simplest bisallene, the C6-isomer 1,2,4,5-hexatetraene (2), this parent system was first prepared by a protocol according to general route (ii) [6]. As summarized in Scheme 1, conversion of the C3-building block propargyl bromide (19) into its Grignard reagent, allenyl

Iridium-catalyzed intramolecular [4 + 2] cycloadditions of alkynyl halides

• Andrew Tigchelaar and
• William Tam

Beilstein J. Org. Chem. 2012, 8, 1765–1770, doi:10.3762/bjoc.8.201

• ). Deprotonation of 8 with sodium hydride, followed by trapping with propargyl bromide provided 9 in 60% yield, and a Mitsunobu reaction between 8 and sulfonamide 10 (prepared as per reference [47]) provided 11 in 74% yield. Bromination of 9 and 11 provided diene-tethered alkynyl halides 1c (57%) and 1e (83

• %), respectively. Synthesis of substrate 1g commenced with deprotonation of diethyl malonate, followed by addition of mesylate 12, and subsequent deprotonation and addition of propargyl bromide as described by Gilbertson [31] to provide dieneyne 13 (Scheme 4). Diene 13 was then treated under the standard

Regioselective synthesis of 7,8-dihydroimidazo[5,1-c][1,2,4]triazine-3,6(2H,4H)-dione derivatives: A new drug-like heterocyclic scaffold

• Nikolay T. Tzvetkov,
• Harald Euler and
• Christa E. Müller

Beilstein J. Org. Chem. 2012, 8, 1584–1593, doi:10.3762/bjoc.8.181

• 25 yielding 27. Reaction of 24 and 25 with propargyl bromide (80% in toluene) under basic conditions at 85 °C yielded the N-propargyl derivatives 28 and 29 (Scheme 3). The final products 26–29 were purified by column chromatography followed by preparative RP-HPLC, or by recrystallization; the pure

• . Synthesis of 7,8-dihydroimidazo[5,1-c][1,2,4]triazine-3,6-diones 23–29. Reagents and conditions: (i) P2S5, dioxane, reflux, 24 h; (ii) hydrazine monohydrate (20 equiv), EtOH, reflux 5–10 h; (iii) MeI (for 26) or methyl methanesulfonate (for 27), NaH, DMF, r.t.; (iv) propargyl bromide (80% in toluene), NaH

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

Asymmetric synthesis of quaternary aryl amino acid derivatives via a three-component aryne coupling reaction

• Elizabeth P. Jones,
• Peter Jones,
• Andrew J. P. White and
• Anthony G. M. Barrett

Beilstein J. Org. Chem. 2011, 7, 1570–1576, doi:10.3762/bjoc.7.185

• examined to determine which electrophiles could be introduced at C-6 (Table 1). Alkylations employing benzyl bromide, allyl bromide and propargyl bromide (Table 1, entries 2, 3 and 5) proceeded smoothly, furnishing the desired products 6b, 6c and 6e in excellent yields and high diastereoselectivity

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

• ][41]. The alkyne 6 required for the synthesis of 2a was obtained from propargyl bromide and 3-formylpyridine oxime (Scheme 6), and those for 2b, 2c, and 2d, following the routes shown in Scheme 7. Reaction of these alkynes with 4 in the presence of copper(II) sulfate, sodium ascorbate and tris[(1

Synthesis of fluoranthenes by hydroarylation of alkynes catalyzed by gold(I) or gallium trichloride

• Sergio Pascual,
• Christophe Bour,
• Paula de Mendoza and
• Antonio M. Echavarren

Beilstein J. Org. Chem. 2011, 7, 1520–1525, doi:10.3762/bjoc.7.178

• lithium with the corresponding propargyl bromide or by Sonogashira couplings of 9-(prop-2-ynyl)-9H-fluorene [61], were cyclized by using gold(I) complex 6 or GaCl3 as the catalyst (Table 3). Although both catalysts could be used for the synthesis of 3-arylfluoranthenes 8b–h, better yields were obtained

One-pot Diels–Alder cycloaddition/gold(I)-catalyzed 6-endo-dig cyclization for the synthesis of the complex bicyclo[3.3.1]alkenone framework

• Boubacar Sow,
• Gabriel Bellavance,
• Francis Barabé and
• Louis Barriault

Beilstein J. Org. Chem. 2011, 7, 1007–1013, doi:10.3762/bjoc.7.114

• ][22]. Results and Discussion The synthesis began by a C-alkylation of enone 8 [23] using LDA and MeI to give the corresponding ketone in 90% yield (Scheme 2). A second alkylation to add the propargyl chain was carried out using LDA and propargyl bromide to afford 9 in 62% yield as an inseparable

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

• situ from the reaction of 2.0 equivalents of indium with 3.0 equivalents of substituted propargyl bromide in the presence of 3.0 equivalents of KI. The best solvent from those that were screened (DMF, THF, C6H6, and C6H5CH3) was found to be DMF. Because further functionalization of the allene group

A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed- bed microreactor

• Andrew Bogdan and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2009, 5, No. 17, doi:10.3762/bjoc.5.17

• catalysts functionalized with an acetylene moiety can be tethered to AO using a Huisgen cycloaddition [39]. Azide-functionalized AO resin (AO-N3, 2) was prepared by treating AO with sodium azide (Scheme 1) [41]. The coupling of 4-hydroxy-TEMPO 3 with propargyl bromide (4) using sodium hydride yielded the

• drop wise to the sodium hydride suspension at 0 °C and stirred until gas evolution ceased. Propargyl bromide (80% in toluene, 800 μL, 7.4 mmol, 1.3 equiv) in DMF (10 mL) was added at 0 °C and the reaction was allowed to warm up to RT and stirred overnight. The reaction was quenched with water and the

Synthesis of 2-substituted 9-oxa-guanines {5-aminooxazolo[5,4-d]pyrimidin- 7(6H)-ones} and 9-oxa-2-thio- xanthines {5-mercaptooxazolo[5,4-d]pyrimidin- 7(6H)-ones}

• Subrata Mandal,
• Wen Tai Li,
• Yan Bai,
• Jon D. Robertus and
• Sean M. Kerwin

Beilstein J. Org. Chem. 2008, 4, No. 26, doi:10.3762/bjoc.4.26

• of 7a by alkylation with methyl iodide, benzyl bromide, propargyl bromide, or methyl 6-O-(tolylsulfonyl)-α-D-glucopyranoside [21] afforded the thioethers 8a–d, respectively. The structural assignment of 8a–d as thioethers rest principally on their 1H and 13C NMR spectra, which contain resonances more