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

• the alkene is quite remarkable, since not only monosubstituted and 1,1-disubstituted olefins participated in the cyclopropanation, but also 1,2-disubstituted alkenes (cis or trans), which previously failed with other chiral transition metal catalysts, providing excellent yields and very good levels of

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

• absence of transition-metal catalysts. A variety of unsymmetrical diaryl selenides can be conveniently prepared by using this arylation method. Keywords: arylation; unsymmetrical diaryl selenide; free radical; organobismuth; photoinduced reaction; Introduction A number of organoselenium compounds are

• affords unsymmetrical diaryl selenides in good yields. This method is efficient, because two arylseleno groups from diaryl selenides can be used as a selenium source, and its advantage is that the reaction proceeds in the absence of transition-metal catalysts. Experimental General comments Compounds 1a

• ][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

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• illustrated by the second transformation in Scheme 26 starting with iodide 141 and leading to dichlorovinyl lactone 142 [57]. It is interesting to note that while sp2–sp2 couplings are readily accomplished starting with vinylic or aromatic iodides using a variety of transition–metal catalysts, especially

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

• afford 2B or 2C (Scheme 8). Further transmetalation of vinyliron intermediate 2B or 2C with R′MgBr yielded the corresponding vinylmagnesium intermediate 2D. Therefore, selective synthesis of both regioisomers of allylic alcohols can be accomplished by simply choosing transition-metal catalysts (Cu or Fe

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

• moderate yields. Keywords: A3 coupling; cooperative catalysis; coumarin synthesis; cycloisomerization; transition-metal catalysts; Introduction An alkyne, an aldehyde and an amine coupling, referred to as A3 coupling [1], has been found as an efficient method for C–N and C–C bond formation that results

• transition-metal catalysts (based on gold, mercury, platinum, silver, etc.), Brønsted acids and electrophilic iodine sources (I2, ICl, NIS) have been used for the transformation. If one of the partners in A3 coupling has any nucleophile for concomitant electrophilic cyclization on the alkyne group in the A3

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

• efficient way of making 6-membered rings, particularly in the case of electronically similar dienes and dienophiles, which can require high temperatures and long reaction times for the thermal cycloaddition to occur [28]. Many different transition-metal catalysts have been described for these types of

C2-Alkylation of N-pyrimidylindole with vinylsilane via cobalt-catalyzed C–H bond activation

• Zhenhua Ding and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2012, 8, 1536–1542, doi:10.3762/bjoc.8.174

• palladium-catalyzed, norbornene-mediated C2-alkylation reaction with a broad spectrum of alkyl bromides [21]. Over the past few years, our group and others have explored C–H bond functionalization reactions using cobalt complexes as inexpensive transition-metal catalysts [22], which often feature mild

Synthesis of axially chiral oxazoline–carbene ligands with an N-naphthyl framework and a study of their coordination with AuCl·SMe₂

• Feijun Wang,
• Shengke Li,
• Mingliang Qu,
• Mei-Xin Zhao,
• Lian-Jun Liu and
• Min Shi

Beilstein J. Org. Chem. 2012, 8, 726–731, doi:10.3762/bjoc.8.81

• . However, while the ligands (Sa,S)-7 gave their corresponding Au complexes (Sa,S)-16 in excellent yields, only modest yields of complexes (Ra,S)-16 were obtained for ligands (Ra,S)-7. Further studies focusing on the preparation of conformationally stable and enantiomerically pure transition-metal catalysts

Ion-exchange-resin-catalyzed adamantylation of phenol derivatives with adamantanols: Developing a clean process for synthesis of 2-(1-adamantyl)-4-bromophenol, a key intermediate of adapalene

• Nan Wang,
• Ronghua Wang,
• Xia Shi and
• Gang Zou

Beilstein J. Org. Chem. 2012, 8, 227–233, doi:10.3762/bjoc.8.23

• derivatives are the key skeletons of synthetic retinoid analogues [1][2][3][4][5][6][7][8][9] and supporting ligands of many homogeneous transition-metal catalysts [10][11][12][13][14]. Introduction of an adamantyl group to the phenol ring has largely relied on acid-catalyzed Friedel–Crafts alkylation with

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

• range of other catalysts by replacing proline with another solid catalyst precursor. We are currently investigating the combination of ligands and solid metal salts to generate transition-metal catalysts continuously. Methods for catalyst use in flow. General reactor setup. A) A glass Omnifit column is

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

• require the use of transition metal catalysts. The preparation of aryl and heteroaryl zinc derivatives is conveniently achieved by three general procedures: the direct insertion of zinc dust to aryl or heteroaryl iodides or bromides; the direct insertion of magnesium in the presence of Zn(II) salts to

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

• cycloadditions involving zwitterionic intermediates similar to I have also been developed with other transition metal catalysts such as tungsten, rhodium or platinum [32][33][34][35]. In particular, important developments were recently achieved with platinum catalysts [36][37], including the first

• cycloaddition reactions. The distinctive properties of these metal complexes compared to other, more conventional, transition metal catalysts (e.g., those based on Rh, Ir, Pd, Ru or Ni complexes) and, in particular, their high carbophilicity and ability to stabilize carbocationic intermediates, has allowed

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• was rather limited in organic synthesis until the advantages of gold complexes as catalysts were discovered [1]. In comparison to other transition-metal catalysts, most gold-catalyzed reactions are atom-economic, remarkably mild with regard to reaction conditions, and most importantly, have a

Highly efficient gold(I)-catalyzed Overman rearrangement in water

• Dong Xing and
• Dan Yang

Beilstein J. Org. Chem. 2011, 7, 781–785, doi:10.3762/bjoc.7.88

• catalysis under very mild conditions [3][4][5][6][7]. Asymmetric induction has been achieved with certain types of transition metal catalysts (e.g., palladium complexes) in combination with chiral ancillary ligands [8][9][10][11][12][13]. However, although a large number of late transition metal catalysts

A gold-catalyzed alkyne-diol cycloisomerization for the synthesis of oxygenated 5,5-spiroketals

• Sami F. Tlais and
• Gregory B. Dudley

Beilstein J. Org. Chem. 2011, 7, 570–577, doi:10.3762/bjoc.7.66

• challenges that required a focused study. For this thematic issue on gold catalysis in organic synthesis, we detail here the challenges and considerations involved in the cycloisomerization of alkynes to oxygenated spiroketals and outline our screening of various late transition metal catalysts and

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor

• Bernhard Gutmann,
• Toma N. Glasnov,
• Tahseen Razzaq,
• Walter Goessler,
• Dominique M. Roberge and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2011, 7, 503–517, doi:10.3762/bjoc.7.59

• Figure S5 in Supporting Information File 1) clearly reveals that the age/history of the reactor can have an influence on the chemical transformations occurring inside these flow devices. The use of transition metal catalysts for carbon–carbon or carbon–heteroatom bond formation under continuous flow

• conditions represents an interesting opportunity for studying the effects of metal contaminations inside of microreactors, as many of these coupling reactions proceed in the presence of extremely small quantities of transition metal catalysts in so-called “homoeopathic” doses [57][58]. In a recent

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• 54b did not give the corresponding alkylated cresol 59. Instead the chromane 60 was observed in 28% yield (Scheme 25). This reaction has recently been improved and extended by applying MoCl(CO)3Cp and [Mo(CO)3Cp]2 as transition-metal catalysts [76]. A very similar FC allylation/hydroaralyation

Can we measure catalyst efficiency in asymmetric chemical reactions? A theoretical approach

• Shaimaa El-Fayyoumy,
• Matthew H. Todd and
• Christopher J. Richards

Beilstein J. Org. Chem. 2009, 5, No. 67, doi:10.3762/bjoc.5.67

• extraordinary efficiency of ligated transition metal catalysts in asymmetric hydrogenation. An analysis of the unit cost of each catalyst reveals these to span a very wide range, with only the amino acid proline comparing favourably with the hydrogenation systems. The ACE formula permits a comparison between

Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with secondary amine nucleophiles

• Dingqiao Yang,
• Ping Hu,
• Yuhua Long,
• Yujuan Wu,
• Heping Zeng,
• Hui Wang and
• Xiongjun Zuo

Beilstein J. Org. Chem. 2009, 5, No. 53, doi:10.3762/bjoc.5.53

• metal catalysts may be used for asymmetric ring-opening reactions of oxabicyclic alkenes. These include complexes of copper [20][21][22][23][24][25], palladium [14][15][26][27][28][29][30][31], iron [32], and nickel [33][34][35][36]. Recently, we reported for the first time iridium-catalyzed asymmetric

• -catalyzed asymmetric ring-opening of oxabenzonorbornadiene with a wide range of nucleophiles including thiols [10], phenols [11], organoboronic acids [12][13], dialkylzincs [14][15], carboxylates [16], sulfur nucleophiles [17], and various amines [18][19]. In addition to rhodium catalysts, other transition

Pd/C- Mediated synthesis of indoles in water

• Mohosin Layek,
• Udaya Lakshmi,
• Dipak Kalita,
• Deepak K. Barange,
• Aminul Islam,
• K. Mukkanti and
• Manojit Pal

Beilstein J. Org. Chem. 2009, 5, No. 46, doi:10.3762/bjoc.5.46

• analogues. A large number of methods [9][10][11][12] have been reported for the construction of indole ring many of which are mediated by transition metal catalysts. Among these methods palladium mediated protocols have gain considerable interest [13]. In our effort towards the development of palladium

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

• potential as continuous flow processes. Realizing this, we developed a catalytic packed-bed microreactor that could be used for the continuous flow oxidation of alcohols to aldehydes or ketones. Oxidations that do not require transition metal catalysts are particularly appealing since there is neither

An exceptional P-H phosphonite: Biphenyl- 2,2'-bisfenchylchlorophosphite and derived ligands (BIFOPs) in enantioselective copper- catalyzed 1,4-additions

• T. Kop-Weiershausen,
• J. Lex,
• J.-M. Neudörfl and
• B. Goldfuss

Beilstein J. Org. Chem. 2005, 1, No. 6, doi:10.1186/1860-5397-1-6

• ; Introduction Chiral monodentate phosphorus ligands with C2-symmetric diol backbones, e.g. with the prominent BINOLs or TADDOLs, are fundamental for the construction of efficient enantioselective transition metal catalysts, especially for copper-catalyzed 1,4-additions. [1][2][3][4][5][6][7][8][9][10][11][12