An intramolecular inverse electron demand Diels–Alder approach to annulated α-carbolines

• Zhiyuan Ma,
• Feng Ni,
• Grace H. C. Woo,
• Sie-Mun Lo,
• Philip M. Roveto,
• Scott E. Schaus and
• John K. Snyder

Beilstein J. Org. Chem. 2012, 8, 829–840, doi:10.3762/bjoc.8.93

• 3-arylpyridines also found application [43][44], and likewise falls into the category of indole ring closure onto an existing substituted pyridine, though in this case with the formation of the C–N bond. More recently, the group of Cuny has reported two strategies that exploit cross-couplings to

Functionalization of heterocyclic compounds using polyfunctional magnesium and zinc reagents

• Paul Knochel,
• Matthias A. Schade,
• Sebastian Bernhardt,
• Georg Manolikakes,
• Albrecht Metzger,
• Fabian M. Piller,
• Christoph J. Rohbogner and
• Marc Mosrin

Beilstein J. Org. Chem. 2011, 7, 1261–1277, doi:10.3762/bjoc.7.147

• readily converted to the desired zinc reagents 31. The Pd-catalyzed cross-coupling of 31 with the iodoquinoline 32 and with S-Phos as ligand [15][16][17] provides the alkaloid papaverine (33) in 68% yield (Scheme 5) [13]. Ni-catalyzed cross-couplings can also be realized [14]. Thus, the reaction of the

• New Pd- and Ni-cross-coupling procedures Although numerous cross-coupling methods have been recently described in the literature [50][51][52], there is still the need for new convenient procedures. We would like to focus on the chemoselectivity problem in cross-couplings in this short section and

• The ability to perform cross-couplings is certainly one of the most versatile functions of heterocyclic zinc intermediates. Recently, we have shown that NiCl2 (0.05 mol %) constitutes an economical method for performing Negishi cross-couplings [18][19], however, it does not solve the problem of the

When cyclopropenes meet gold catalysts

• Frédéric Miege,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2011, 7, 717–734, doi:10.3762/bjoc.7.82

• this gold powder (MeCN, 60 °C), 3,3-diphenylcyclopropene (1) gave 1,1,6,6-tetraphenylhexa-1,3,5-triene (45), arising from self-coupling of a surface bound gold carbene, as a 40:60 mixture of Z/E-geometric isomers (82%). Cross-couplings of carbenes derived from cyclopropene 1 and phenyldiazomethane or

An efficient and practical entry to 2-amido-dienes and 3-amido-trienes from allenamides through stereoselective 1,3-hydrogen shifts

• Ryuji Hayashi,
• John B. Feltenberger,
• Andrew G. Lohse,
• Mary C. Walton and
• Richard P. Hsung

Beilstein J. Org. Chem. 2011, 7, 410–420, doi:10.3762/bjoc.7.53

• ][57][58]) suffer from limited access as well as the instability of halo-dienes (Scheme 2). In contrast, multi-substituted allenamides can be concisely prepared through α-alkylations of a parent allenamide [47][59] (for the synthesis of parent allenamides see [60]) or amidative cross-couplings of

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• , arylsulfonyl chlorides and arenediazonium salts with arylboronic acids that gave biaryls in good to excellent yields [28][31][32]. As part of our ongoing investigations aimed at the development of transition metal catalysis, we report here that the Suzuki–Miyaura cross-couplings of 1-aryltriazenes with

• cooling and the resulting precipitate isolated by filtration. The damp solid was recrystallized from EtOH and dried under reduced pressure. General procedure for the Suzuki–Miyaura cross-couplings of 1-aryltriazenes and arylboronic acids Polystyrene-supported Pd–NHC catalyst 1 (100 mg, 10 μmol Pd), 1

Pd-catalyzed decarboxylative Heck vinylation of 2-nitrobenzoates in the presence of CuF₂

• Lukas J. Gooßen,
• Bettina Zimmermann and
• Thomas Knauber

Beilstein J. Org. Chem. 2010, 6, No. 43, doi:10.3762/bjoc.6.43

• protodecarboxylation of particularly electron-rich, ortho-substituted benzoic acids, e.g. 2,6-dimethoxybenzoic acid, whereas electron-poor derivatives are not easily decarboxylated. The palladium-catalyzed protodecarboxylation reported by Kozlowski [25], and the palladium-catalyzed decarboxylative cross-couplings

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

• possible palladium-catalyzed cross-couplings we performed several Sonogashira-reactions [28][29][30]. As described in Scheme 3, the pyridinyl-bistriflates or -nonaflates 3 were coupled with alkynes like phenylacetylene or (triisopropylsilyl)acetylene using Pd(PPh3)4 or alternatively, Pd(OAc)2/PPh3 as

Efficient and improved synthesis of Telmisartan

• A. Sanjeev Kumar,
• Samir Ghosh and
• G. N. Mehta

Beilstein J. Org. Chem. 2010, 6, No. 25, doi:10.3762/bjoc.6.25

• iodides 5 and 6 using 5 equiv of copper [7]. Modern syntheses of 7 involve cross-couplings of sensitive aryl magnesium [8], zinc [9], or boron [10][11] compounds with alkyl 2-halobenzoates. Since the commercialization of Telmisartan, 7 has become readily available at low cost, so that most subsequent

Palladium- catalyzed cross coupling reactions of 4-bromo- 6H-1,2-oxazines

• Reinhold Zimmer,
• Elmar Schmidt,
• Michal Andrä,
• Marcel-Antoine Duhs,
• Igor Linder and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2009, 5, No. 44, doi:10.3762/bjoc.5.44

• furnishing 4,5-dichloro-substituted compound 7a as a by-product in 13% yield. With the 4-halogenated 6H-1,2-oxazines 2 and 6 in hand, palladium-catalyzed cross couplings offer an efficient and useful approach for the synthesis of novel functionalized 6H-1,2-oxazines. The Suzuki-coupling of the 4-bromo

• the expected product 9d and a byproduct bearing a 4-enyne moiety at 4-position. This indicates an addition of a second alkyne molecule to the primary product 9. Similar results were observed for the Sonogashira reaction of 2a with propargylic alcohol [33]. After successful simple cross couplings of

Polyionic polymers – heterogeneous media for metal nanoparticles as catalyst in Suzuki–Miyaura and Heck–Mizoroki reactions under flow conditions

• Klaas Mennecke and
• Andreas Kirschning

Beilstein J. Org. Chem. 2009, 5, No. 21, doi:10.3762/bjoc.5.21

• heterogeneous supports for palladium(0) nanoparticles is described. These functionalized polymers were incorporated inside a flow reactor and employed in Suzuki–Miyaura and Heck cross couplings under continuous flow conditions. Keywords: Heck–Mizoroki reaction; heterogeneous catalysis; ion exchange resin

Convenient methods for preparing π-conjugated linkers as building blocks for modular chemistry

• Jiří Kulhánek,
• Filip Bureš and
• Miroslav Ludwig

Beilstein J. Org. Chem. 2009, 5, No. 11, doi:10.3762/bjoc.5.11

• crucial for such a synthetic approach. Hence, we report here a convenient synthesis as well as characterization of either unsubstituted (R = H) or donor substituted (R = NMe2, OMe) π-conjugated linkers designed for the Suzuki–Miyaura and Sonogashira cross-couplings with a systematically varied and