Enantioselective reduction of ketoimines promoted by easily available (S)-proline derivatives

• Martina Bonsignore,
• Maurizio Benaglia,
• Laura Raimondi,
• Manuel Orlandi and
• Giuseppe Celentano

Beilstein J. Org. Chem. 2013, 9, 633–640, doi:10.3762/bjoc.9.71

• selectivity was achieved by tuning the metal catalyst. In the trichlorosilane-mediated reductions in this work we aimed to exploit the imine activation by the acid proton of the carboxylic group, which can act at the same time as a Lewis basic site to coordinate the silicon atom and hopefully control the

New simple synthesis of ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thiones: Direct formation from carbon disulfide and (E)-3-(2-aminoaryl)acrylates or (E)-3-(2-aminoaryl)acrylonitriles

• Qiuping Ding,
• Yuqing Lin,
• Guangni Ding,
• Fumin Liao,
• Xiaoyan Sang and
• Yi-Yuan Peng

Beilstein J. Org. Chem. 2013, 9, 460–466, doi:10.3762/bjoc.9.49

• and efficient method to construct ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thione derivatives has been developed from carbon disulfide and (E)-3-(2-aminoaryl)acrylates or (E)-3-(2-aminoaryl)acrylonitriles under mild conditions, without the need for a metal catalyst. The newly developed method

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

• cyclopropenes Increasing the reactivity of alkynes and alkenes is another strategy to achieve intermolecular carbometalation reactions. For example, strained alkenes are highly reactive toward carbometalation. The reactions of cyclopropenes took place without the aid of a metal catalyst (Scheme 16) [81

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

• aminoindolizines, 2-(aminomethyl)indoles, imidazopyridines, butenolides and 1,2-dihydroisoquinoline derivatives, respectively, combining these two approaches successfully. Along the same lines, we investigated a reaction between ethoxyacetylene, pyrrolidine and salicylaldehyde in the presence of a transition-metal

• catalyst. That, after consecutive A3 coupling, cycloisomerization and hydrolysis of the resultant vinyl ether intermediate, should produce coumarins (Scheme 1, (d)). The reason for the selective 6-endo-dig cyclization of such a cooperative-catalysis reaction has been well documented through DFT

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

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

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

• –94%). These results are the first examples of cycloadditions of alkynyl halides using an iridium catalyst. Keywords: alkynyl halide; cycloaddition; diene-tethered alkyne; iridium; transition-metal catalyst; Introduction Iridium complexes have been used as catalysts for a wide variety of reactions

Arylglycine-derivative synthesis via oxidative sp³ C–H functionalization of α-amino esters

• Zhanwei Xu,
• Xiaoqiang Yu,
• Xiujuan Feng and
• Ming Bao

Beilstein J. Org. Chem. 2012, 8, 1564–1568, doi:10.3762/bjoc.8.178

•  1, reactions 1–3). However, these reactions need expensive arylboronic acids (Petasis reaction) [4][5][6][7][8][9] and suitable leaving groups [10][11][12] as well as a metal catalyst (Polonovsky reaction; this route requires the preparation of amine N-oxide in advance) [13][14]. We have recently

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

• cleavage seems to depend on the nature of the metal catalyst. Nevertheless, these results do provide inspiration for the development of similar C–H functionalization catalysis involving metal carbenes or silylenes (or perhaps even electrophilic nitrenes). Utility of M═E FLPs in C–H functionalization Given

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

• 1,2-hydride shift to intermediate 27 followed by elimination of the metal catalyst [25] to afford the observed cyclopropane product 6. An alternative reaction pathway may be invoked for the ethyl-substituted substrate 22 leading to product 23 (Scheme 4). After initial cyclization of the enol ether

Double N-arylation reaction of polyhalogenated 4,4’-bipyridines. Expedious synthesis of functionalized 2,7-diazacarbazoles

• Mohamed Abboud,
• Emmanuel Aubert and
• Victor Mamane

Beilstein J. Org. Chem. 2012, 8, 253–258, doi:10.3762/bjoc.8.26

• -pentylaniline (6a) was investigated with several ligands in toluene at 120 °C, and in the presence of Pd2(dba)3 as the source of metal catalyst (Scheme 2). Ligands such as Xantphos [33], biaryl monophosphines [34] and t-Bu3P [35] were tested since they were found to be very effective in the selective C-5

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• -4,5-diyl)dimethanol. Phenyl-TADDOL (T1) = tetraphenyl-(2,2-dimethyl-1,3-dioxolane) derivative; 1-naphthyl-TADDOL (T2) = tetra-1-naphthyl-(2,2-dimethyl-1,3-dioxolane) derivative. Halogenation of β-ketocarbonyl compounds: Importance of enolization and the potential role of a metal catalyst. Qualitative

Scaling up of continuous-flow, microwave-assisted, organic reactions by varying the size of Pd-functionalized catalytic monoliths

• Ping He,
• Stephen J. Haswell,
• Paul D. I. Fletcher,
• Stephen M. Kelly and
• Andrew Mansfield

Beilstein J. Org. Chem. 2011, 7, 1150–1157, doi:10.3762/bjoc.7.133

• the Pd-monolith catalyst The Suzuki–Miyaura reaction is a widely used method in organic synthesis for the selective formation of aryl–aryl carbon–carbon bonds in the synthesis of high-value fine chemicals and intermediates in the pharmaceutical industry. This reaction requires a metal catalyst, such

Efficient gold(I)/silver(I)-cocatalyzed cascade intermolecular N-Michael addition/intramolecular hydroalkylation of unactivated alkenes with α-ketones

• Ya-Ping Xiao,
• Xin-Yuan Liu and
• Chi-Ming Che

Beilstein J. Org. Chem. 2011, 7, 1100–1107, doi:10.3762/bjoc.7.126

• conducted on the design and utilization of dual-metal catalyst systems in organic synthesis [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] (for recent examples of Au/Pd-cocatalysis see [30][31][32][33]; for Au/Mo-cocatalysis see [31][35]; for Au/Ag-cocatalysis see [36][37][38]; for Au/Yb

• ]. Using a combination of 5 mol % of (t-Bu)2(o-diphenyl)PAuCl and 15 mol % of AgOTf as a dual-metal catalyst system lead to the formation of pyrrolidine derivative 3a as a 5.3:1 mixture of two diastereomers in 67% yield (Table 1, entry 4). The yield increased from 58% to 67% as the mol ratio of 2a to 1a

• mixture did not have a noticeable effect on the yield of 3a (Table 1, entries 8–11). To identify further the optimal reaction conditions for the gold(I)/silver(I)-cocatalyzed cascade reaction, a number of dual-metal catalyst systems, composed of 15 mol % of silver salt with 5 mol % of gold(I) complex in

Recent developments in gold-catalyzed cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2011, 7, 1075–1094, doi:10.3762/bjoc.7.124

• allenyl acetates of type XXII (Figure 1, R ≠ H), species which can be additionally activated by the metal catalyst to afford a wide range of gold-catalyzed transformations. Theoretical studies showed that all these species are in rapid equilibrium and the reactivity of the system depends not only on the

• allenic esters 42; compounds which evolve in situ in the presence of the same metal catalyst to give adducts resulting from formal (3 + 2) and/or (2 + 2) annulation processes (Scheme 23). In the presence of Ph3PAuCl/AgSbF6, the (2 + 2) cycloaddition is favored furnishing 43 (upper arrow) [85]. However

Au(I)/Au(III)-catalyzed Sonogashira-type reactions of functionalized terminal alkynes with arylboronic acids under mild conditions

• Deyun Qian and
• Junliang Zhang

Beilstein J. Org. Chem. 2011, 7, 808–812, doi:10.3762/bjoc.7.92

• , pharmaceuticals and other materials [1][2][3]. In the past decade, considerable efforts have been made to enhance the efficiency and generality of this reaction. All kinds of palladium catalyst systems [4][5][6][7][8][9][10] and other metal catalyst systems [3] have been developed for facilitating the Sonogashira

Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium–arene complexes

• Yannick Borguet,
• Xavier Sauvage,
• Guillermo Zaragoza,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2010, 6, 1167–1173, doi:10.3762/bjoc.6.133

• presence of Et3N [34]. This procedure guaranteed the absence of any residual metal catalyst coming from the RCM reaction. A solution of 2-cyclohexenyl trichloroacetamide 5 in toluene was heated for 2 h at 160 °C in the presence of various ruthenium initiators (1 mol %). Conversion into racemic product 6

From discovery to production: Scale- out of continuous flow meso reactors

• Peter Styring and
• Ana I. R. Parracho

Beilstein J. Org. Chem. 2009, 5, No. 29, doi:10.3762/bjoc.5.29

• applications. In an ideal case [16] the catalyst can be recovered and reused several times before it eventually deactivates. At the same time, catalyst recovery can also reduce the environmental pollution caused by heavy metals used in the catalyst systems. When using a supported metal catalyst, another

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

• heterogenization of transition metals. A major hurdle for industrial applications of heterogenized homogeneous metal catalyst is associated with keeping metal leaching down to a minimum. Immobilization can be regarded as one enabling technique in organic chemistry [5][6] that in conjunction with continuous flow

Transition- metal/Lewis acid free synthesis of acyl benzothiophenes via C-C bond forming reaction

• Sarbani Pal,
• Mohammad Ashrafuddin Khan,
• P. Bindu and
• P. K. Dubey

Beilstein J. Org. Chem. 2007, 3, No. 35, doi:10.1186/1860-5397-3-35

• an expensive transition metal catalyst along with toxic carbon monoxide gas[13] or unstable diazo compounds,[18] or pyrophoric BuLi,[19][20] or a multistep synthesis of starting material.[14] The simplest and straightforward method for the synthesis of acyl benzothiophenes appeared to be the Friedel