Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

• these three steps simultaneously in one-pot, however, as isocyanides are also good ligands to transition metals, the Ugi products were only obtained in low yield (19%) without observing any triazole product. Even more interestingly was the copper-free procedure published by the group of Cai, especially

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• involving higher oxidation states from Au(I) precatalysts have been achieved by the addition of a stoichiometric oxidant enabling two-electron redox cycles typically exhibited by other late transition metals. With respect to Ag(I)-mediated MCRs, less information can be found in the literature about the

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• nucleophiles seem to give a roughly 8:1 anti/syn-selectivity. The larger organovinyl reagents give slightly lower anti-selectivities of about 3:1 to 5:1. Highest selectivities are reached with transition metals, such as Rh and Ni (Table 1, entries 12, 18 and 19). The anti-selectivity can be enhanced either by

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• strategies Differently from many transition metals, usually gold is not subjected to redox processes during the catalytic cycles. However, in recent years it has been demonstrated that both [Au(I)/Au(III)] (i.e. monometallic catalytic systems) and [Au(I)Au(I)/Au(II)Au(II)] (i.e. bimetallic catalytic systems

Recent advances in transition metal-catalyzed Csp²-monofluoro-, difluoro-, perfluoromethylation and trifluoromethylthiolation

• Grégory Landelle,
• Armen Panossian,
• Sergiy Pazenok,
• Jean-Pierre Vors and
• Frédéric R. Leroux

Beilstein J. Org. Chem. 2013, 9, 2476–2536, doi:10.3762/bjoc.9.287

• moieties have been reported in the literature [27][33][34][35][36][37][38][39][40][41], the incorporation of partially fluorinated methyl groups is still underdeveloped [42][43]. In most cases transition metals have to be employed in stoichiometric amounts. 1.1 Palladium catalysis The first

Gold(I)-catalyzed enantioselective cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

• core of frondosins (for example, 5a), in 68% yield and 90% ee (Scheme 4). Since this bicyclic enone was previously elaborated into frondosin A and B, the approach represented a streamlined formal enantioselective synthesis of both molecules. Analogous to other transition metals from groups eight to

Gold-catalyzed reaction of oxabicyclic alkenes with electron-deficient terminal alkynes to produce acrylate derivatives

• Yin-wei Sun,
• Qin Xu and
• Min Shi

Beilstein J. Org. Chem. 2013, 9, 1969–1976, doi:10.3762/bjoc.9.233

• ]. It is well known that gold catalysts have different catalytic abilities compared with other transition metals [24]. Moreover, gold-catalyzed chemical transformations have made significant progress during the last 5 years [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44

Homolytic substitution at phosphorus for C–P bond formation in organic synthesis

• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 1269–1277, doi:10.3762/bjoc.9.143

• . Advantageously, it requires neither highly basic conditions nor transition metals. Homolytic substitution at phosphorus is still in its infancy. In light of the rich chemistry of organophosphorus compounds, it will find wider application in organic synthesis in the future. Calculated reaction profile of

Transition-metal and organocatalysis in natural product synthesis

• David Yu-Kai Chen and
• Dawei Ma

Beilstein J. Org. Chem. 2013, 9, 1192–1193, doi:10.3762/bjoc.9.134

• modes of activation, which rival or at times surpass those exhibited by transition metals. Last but not least, the judiciary combination of transition-metal and organic mediators, together with tandem processes encompassing multiple reaction cycles in a programmed sequence, represents a new horizon with

Photoinduced synthesis of unsymmetrical diaryl selenides from triarylbismuthines and diaryl diselenides

• Yohsuke Kobiki,
• Shin-ichi Kawaguchi,
• Takashi Ohe and
• Akiya Ogawa

Beilstein J. Org. Chem. 2013, 9, 1141–1147, doi:10.3762/bjoc.9.127

• ][24][25][26][27][28][29][30][31][32]. Most of these methods use coupling reactions catalyzed by transition-metal complexes. To avoid the contamination of product selenides with transition-metals, the development of synthetic methods for unsymmetrical diaryl selenides in the absence of transition-metal

Asymmetric Diels–Alder reaction with >C=P– functionality of the 2-phosphaindolizine-η¹-P-aluminium(O-menthoxy) dichloride complex: experimental and theoretical results

• Rajendra K. Jangid,
• Nidhi Sogani,
• Neelima Gupta,
• Raj K. Bansal,
• Moritz von Hopffgarten and
• Gernot Frenking

Beilstein J. Org. Chem. 2013, 9, 392–400, doi:10.3762/bjoc.9.40

• chiral auxiliaries [3][4]. Chiral phosphines constitute a very important group of ligands as their coordination compounds with transition metals have been extensively employed in asymmetric catalysis to convert achiral compounds into enantio-enriched products with high efficiency and enantioselectivity

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• reactions are efficient and direct routes to prepare complex and stereodefined organomagnesium and organozinc reagents. However, carbon–carbon unsaturated bonds are generally unreactive toward organomagnesium and organozinc reagents. Thus, transition metals were employed to accomplish the carbometalation

• hydroxymethyl group are also known [86][87][88][89]. Notably, Fox reported the enantio- and stereoselective carbomagnesiation of cyclopropenes without the addition of transition metals (Scheme 21) [90]. The key to successful reactions is the addition of aminoalcohol 3c and 1 equiv of methanol. In 2009, Fox et

Tandem aldehyde–alkyne–amine coupling/cycloisomerization: A new synthesis of coumarins

• Maddi Sridhar Reddy,
• Nuligonda Thirupathi and
• Madala Haribabu

Beilstein J. Org. Chem. 2013, 9, 180–184, doi:10.3762/bjoc.9.21

• in equivalence of reductive alkylation of amines while at the same time appending an alkyne, i.e., a highly useful moiety for further functionlization. This three-component coupling has been accomplished with a very broad range of transition metals, including copper, silver, gold, ruthenium/copper

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• transformations on the multiscale level paves the way to cheaper processes, resulting in minimal waste production and raising the possibility of application in multistep synthetic sequences. Many transition metals, including Pd, Au, Ru, Rh, Cu, and Pt, have been proven to be highly efficient for the formation of

• new bonds without prefunctionalized starting materials [4][5][6][7][8][9][10]. Among the transition metals suitable for this purpose, palladium plays a pivotal role due to its versatility in different synthetic protocols and tolerance towards many functional groups, often avoiding the need for

Synthesis of conformationally restricted glutamate and glutamine derivatives from carbonylation of orthopalladated phenylglycine derivatives

• Esteban P. Urriolabeitia,
• Eduardo Laga and
• Carlos Cativiela

Beilstein J. Org. Chem. 2012, 8, 1569–1575, doi:10.3762/bjoc.8.179

• selective functionalization of organic molecules is, at the present time, one of the most developed areas of organic and organometallic chemistry. Several factors have contributed to this spectacular growth. The main one is the use of transition metals, such as Rh, Ru, Pd, Pt or Au, with the capability of

Metal–ligand multiple bonds as frustrated Lewis pairs for C–H functionalization

• Matthew T. Whited

Beilstein J. Org. Chem. 2012, 8, 1554–1563, doi:10.3762/bjoc.8.177

• number of unsaturated main-group compounds can exhibit electronic properties and reactivity reminiscent of transition metals [3]. A different approach was pioneered by Stephan, who demonstrated that appropriately encumbered (i.e., "frustrated") Lewis acids and bases could achieve synergistic heterolytic

• have extended the approach to include transition metals as Lewis acids and bases [7][8]. In this review, we show that the FLP concept may be extended to encompass certain metal–ligand multiply bonded species, provided that the metal retains an open coordination site to facilitate cooperative reactivity

• . Such complexes may activate various substrates through the combined action of filled and empty orbitals on adjacent atoms: a hybrid of the classical Dewar–Chatt–Duncanson paradigm and normal FLP reactivity [9][10]. M═E FLPs include two limiting scenarios: (1) early, electropositive transition metals in

Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels–Alder reactions

• Stefan Bräse,
• Nicole Volz,
• Franziska Gläser and
• Martin Nieger

Beilstein J. Org. Chem. 2012, 8, 1385–1392, doi:10.3762/bjoc.8.160

• metal-free, usually nontoxic, stable, moisture-insensitive, and often easy to obtain. Because of their inertness towards oxygen and moisture, the use of absolute solvents, inert atmosphere, low temperature, etc., is, in many instances, not required. Furthermore, due to the absence of transition metals

Synthesis of new pyrrole–pyridine-based ligands using an in situ Suzuki coupling method

• Matthias Böttger,
• Björn Wiegmann,
• Steffen Schaumburg,
• Peter G. Jones,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2012, 8, 1037–1047, doi:10.3762/bjoc.8.116

• of chemistry. The pyrrole–pyridine structural motif is featured in current studies, owing to its complexation properties towards first-row transition metals (Fe, Co, Ni, Cu, Zn) [18] and ruthenium [19]. The intramolecular proton transfer of these species is also of interest for vibrational

Regioselective chlorination and bromination of unprotected anilines under mild conditions using copper halides in ionic liquids

• Han Wang,
• Kun Wen,
• Nurbiya Nurahmat,
• Yan Shao,
• He Zhang,
• Chao Wei,
• Ya Li,
• Yongjia Shen and
• Zhihua Sun

Beilstein J. Org. Chem. 2012, 8, 744–748, doi:10.3762/bjoc.8.84

• reported several decades ago with chloride salts of several transition metals [5]. Copper(II) chloride (1) was found to be one of the best reagents for this transformation, which yielded mostly the para-chlorinated product with minor ortho- and dichlorinated products. The mechanism was believed to be

Synthesis and mesomorphic properties of calamitic malonates and cyanoacetates tethered to 4-cyanobiphenyls

• Katharina C. Kress,
• Martin Kaller,
• Kirill V. Axenov,
• Stefan Tussetschläger and
• Sabine Laschat

Beilstein J. Org. Chem. 2012, 8, 371–378, doi:10.3762/bjoc.8.40

• malonates and cyanoacetates are well known as suitable ligands for strong coordination of main-group and transition metals [25]. Benzylidene derivatives of malonic esters, so called swallow-tailed liquid crystals, were described as forming smectic phases [26]. However, most work on liquid-crystalline

Self-assembly of Ru₄ and Ru₈ assemblies by coordination using organometallic Ru(II)₂ precursors: Synthesis, characterization and properties

• Sankarasekaran Shanmugaraju,
• Dipak Samanta and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2012, 8, 313–322, doi:10.3762/bjoc.8.34

• . In general, the utilization of functional properties would be realized more from macrocycles containing transition metals, due to their high sensitivity towards various external stimuli, compared to purely organic macrocycles. In this regard, substantial efforts have been devoted to the design of

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

• compound 45 failed to extract any cations. 4.2.3 Transition metals: The tris(diphenylphosphine) derivative 26 prepared by Matt [40] was reacted with [Mo(CO)3(cycloheptatriene)] to give a complex that was determined to be the symmetrically bound Mo(CO)3 complex involving all three of the phosphorus donors

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

• Antonio Avellaneda,
• Courtney A. Hollis,
• Xin He and
• Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

• greater steric bulk and do not form carbanions with the requisite stability, respectively. In this regard, precursor active methylene compounds with functional groups that are able to coordinate transition metals in the 3-position and a nitro group para to the methylene are under investigation in our

Continuous proline catalysis via leaching of solid proline

• Suzanne M. Opalka,
• Ashley R. Longstreet and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2011, 7, 1671–1679, doi:10.3762/bjoc.7.197

• precursors) that only partially or slowly dissolve into or react with the solution. (See Figure 1 for a comparison of solid catalysts that are used in flow.) Proline is an example of such a catalyst [19] (others include zero-valent transition metals, many solid acid catalysts, and other secondary amine

Efficient synthesis of 1,3-diaryl-4-halo-1H-pyrazoles from 3-arylsydnones and 2-aryl-1,1-dihalo-1-alkenes

• Yiwen Yang,
• Chunxiang Kuang,
• Hui Jin,
• Qing Yang and
• Zhongkui Zhang

Beilstein J. Org. Chem. 2011, 7, 1656–1662, doi:10.3762/bjoc.7.195

• [9] and fungicides [10], and as well as antiviral [11] and antibacterial agents [12]. Pyrazoles are gaining interest as ligands for transition metals, and in the field of materials chemistry [13][14]. Pyrazole and its derivatives can be synthesized by several methods [15]. The most common approach is