Metal-free formal synthesis of phenoxazine

• Gabriella Kervefors,
• Antonia Becker,
• Chandan Dey and
• Berit Olofsson

Beilstein J. Org. Chem. 2018, 14, 1491–1497, doi:10.3762/bjoc.14.126

• recently, Bolm and co-workers reported a metal-free cyclization of iodo-substituted diaryl ethers with a broad scope (Scheme 1b) [18]. Transition metal-catalyzed cross couplings have also been employed to form the required C–O and C–N bonds, e.g., by Cu-catalyzed cyclization of 2-(2-bromophenoxy)anilines

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

• Kimihiro Komeyama,
• Shunsuke Sakiyama,
• Kento Iwashita,
• Itaru Osaka and
• Ken Takaki

Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

• organometallics, involving a wide range of transition metal-catalyzed reactions. For example, transmetalation between an organonickel (or organocobalt) complex and chromium salt results in the formation of a highly nucleophilic organochromium species, which enables efficient addition to aldehydes to give

Rhodium-catalyzed C–H functionalization of heteroarenes using indoleBX hypervalent iodine reagents

• Erwann Grenet,
• Ashis Das,
• Paola Caramenti and
• Jérôme Waser

Beilstein J. Org. Chem. 2018, 14, 1208–1214, doi:10.3762/bjoc.14.102

• ), which ends up on the pyridinone ring. As alternative, a Suzuki–Miyaura coupling between 3-halogenoindoles and (2-methoxypyridyl)boronic acids followed by a deprotection of the methoxy group [7][8] or transition-metal-catalyzed annulation methods [9] have also been reported. In contrast, several

• (III) catalyst for C-5 and C-6 functionalization, respectively [13]. Hypervalent iodine reagents in general [20], and benziodoxole derivatives in particular [21], have found broad application in synthetic chemistry. Aryl iodonium salts have been used successfully in transition-metal-catalyzed

Chlorination of phenylallene derivatives with 1-chloro-1,2-benziodoxol-3-one: synthesis of vicinal-dichlorides and chlorodienes

• Zhensheng Zhao and
• Graham K. Murphy

Beilstein J. Org. Chem. 2018, 14, 796–802, doi:10.3762/bjoc.14.67

• - and vinyl chlorides are highly sought-after intermediates for effecting allylations, and for use in transition metal-catalyzed carbon–carbon and carbon–heteroatom bond-forming reactions [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Given the versatility of allyl chloride and β

Bromide-assisted chemoselective Heck reaction of 3-bromoindazoles under high-speed ball-milling conditions: synthesis of axitinib

• Jingbo Yu,
• Zikun Hong,
• Xinjie Yang,
• Yu Jiang,
• Zhijiang Jiang and
• Weike Su

Beilstein J. Org. Chem. 2018, 14, 786–795, doi:10.3762/bjoc.14.66

• transition-metal-catalyzed reactions [1][2], which has shown itself as a powerful synthetic tool in both academic and industrial practice [3][4][5][6][7]. The transformation has been enrolled as key steps for numerous synthetic routes, including the recent President Green Chemistry Award winner route of

Cobalt-catalyzed directed C–H alkenylation of pivalophenone N–H imine with alkenyl phosphates

• Wengang Xu and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2018, 14, 709–715, doi:10.3762/bjoc.14.60

• alkenylation reaction of pivalophenone N–H imine with an alkenyl phosphate. The reaction tolerates various substituted pivalophenone N–H imines as well as cyclic and acyclic alkenyl phosphates. Keywords: alkenylation; C–C bond formation; C–H activation; cobalt; imine; Introduction Transition-metal-catalyzed

Palladium-catalyzed ortho-halogenations of acetanilides with N-halosuccinimides via direct sp² C–H bond activation in ball mills

• Zi Liu,
• Hui Xu and
• Guan-Wu Wang

Beilstein J. Org. Chem. 2018, 14, 430–435, doi:10.3762/bjoc.14.31

• construction of C–X bonds. With the development of transition-metal-catalyzed cross-coupling reactions, a series of halogenations at the ortho-position of the directing groups have been disclosed [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Nevertheless, from the viewpoint of green chemistry, the

Comparative profiling of well-defined copper reagents and precursors for the trifluoromethylation of aryl iodides

• Peter T. Kaplan,
• Jessica A. Lloyd,
• Mason T. Chin and
• David A. Vicic

Beilstein J. Org. Chem. 2017, 13, 2297–2303, doi:10.3762/bjoc.13.225

• bear the trifluoromethyl group have great importance in the life sciences and materials fields as well as discovery chemistry in general [1][2][3]. Consequently, transition-metal-catalyzed methods for preparing aromatic trifluoromethyl compounds from readily available aryl halides are an area that has

Synthesis of substituted Z-styrenes by Hiyama-type coupling of oxasilacycloalkenes: application to the synthesis of a 1-benzoxocane

• James R. Vyvyan,
• Courtney A. Engles,
• Scott L. Bray,
• Erik D. Wold,
• Christopher L. Porter and
• Mikhail O. Konev

Beilstein J. Org. Chem. 2017, 13, 2122–2127, doi:10.3762/bjoc.13.209

• ; palladium; silicon; Introduction The development of transition metal-catalyzed cross-coupling technologies over the last four decades revolutionized the synthetic chemistry. Indeed, the importance of Pd-catalyzed coupling was recognized with the 2010 Nobel Prize awarded to Heck, Negishi and Suzuki [1][2

Difunctionalization of alkenes with iodine and tert-butyl hydroperoxide (TBHP) at room temperature for the synthesis of 1-(tert-butylperoxy)-2-iodoethanes

• Hao Wang,
• Cui Chen,
• Weibing Liu and
• Zhibo Zhu

Beilstein J. Org. Chem. 2017, 13, 2023–2027, doi:10.3762/bjoc.13.200

• starting materials in a single operation [1][2][3][4][5][6]. Traditional studies have mainly focused on transition-metal-catalyzed direct vicinal difunctionalization of alkenes by installing two substituents across the C=C double bond to form two new bonds or two new functional groups [7][8][9], such as

Transition-metal-free synthesis of 3-sulfenylated chromones via KIO₃-catalyzed radical C(sp²)–H sulfenylation

• Yanhui Guo,
• Shanshan Zhong,
• Li Wei and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2017, 13, 2017–2022, doi:10.3762/bjoc.13.199

• . Presently, the most popular approaches in constructing a C(sp2)–S bond are the transition-metal-catalyzed Ullmann C–S coupling reaction [4][5][6][7][8], Chan–Lam cross-coupling reaction [9][10][11][12] as well as the transition-metal-catalyzed C–H bond activation [13][14][15]. Recently, as a new trend, the

Solvent-free and room temperature synthesis of 3-arylquinolines from different anilines and styrene oxide in the presence of Al₂O₃/MeSO₃H

• Hashem Sharghi,
• Mahdi Aberi,
• Mohsen Khataminejad and
• Pezhman Shiri

Beilstein J. Org. Chem. 2017, 13, 1977–1981, doi:10.3762/bjoc.13.193

• ]. Transition metal-catalyzed processes [5][6][7][8] and metal-free paths [9][10][11] are two general approaches for the synthesis of this type of compounds. However, the existing methods suffer from complicated multistep processes, limited availability of substrates, toxic organic solvents, long reaction times

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• ]. Advantageously this methodology was applicable for both solid and liquid olefins. Mechanochemical C–H functionalization Transition-metal-catalyzed activation and functionalization of inert C–H bonds of organic molecules provides a broad avenue in the synthesis of wide range of compounds. In 2015, Bolm and co

Synthesis of benzothiophene and indole derivatives through metal-free propargyl–allene rearrangement and allyl migration

• Jinzhong Yao,
• Yajie Xie,
• Lianpeng Zhang,
• Yujin Li and
• Hongwei Zhou

Beilstein J. Org. Chem. 2017, 13, 1866–1870, doi:10.3762/bjoc.13.181

• (Figure 1) [7][8][9]. Moreover, benzothiophenes have extensive applications in materials science. Besides the traditional methods of transition metal-catalyzed cyclization of alkyne substrates [10][11][12], the synthesis of benzothiophenes via metal-free conditions has recently aroused much attention [13

Ni nanoparticles on RGO as reusable heterogeneous catalyst: effect of Ni particle size and intermediate composite structures in C–S cross-coupling reaction

• Debasish Sengupta,
• Koushik Bhowmik,
• Goutam De and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 1796–1806, doi:10.3762/bjoc.13.174

• showing comparative catalytic efficiency and NP sizes). Mechanistically, the transition-metal-catalyzed C–S cross-coupling reaction, using mainly Pd, Cu or Ni species, is believed to proceed through three major steps; viz. the initial oxidative addition, then substitution by thiolate anion and finally the

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• section we turn our attention to transition metal-catalyzed aerobic dehydrogenation of C–C and C–N bonds. Molecular oxygen is well established as an oxidant for oxidative dehydrogenation of heterocycles. These reactions occur under open air or excess oxygen pressure. They are classified as aerobic

Encaging palladium(0) in layered double hydroxide: A sustainable catalyst for solvent-free and ligand-free Heck reaction in a ball mill

• Wei Shi,
• Jingbo Yu,
• Zhijiang Jiang,
• Qiaoling Shao and
• Weike Su

Beilstein J. Org. Chem. 2017, 13, 1661–1668, doi:10.3762/bjoc.13.160

• easily recovered and reused for at least five times without significant loss of catalytic activity. Keywords: ball milling; Heck reaction; layer double hydroxides; solvent-free; supported Pd catalyst; Introduction High-speed ball milling (HSBM)-assisted transition metal-catalyzed cross-coupling reactions

Base-promoted isomerization of CF₃-containing allylic alcohols to the corresponding saturated ketones under metal-free conditions

• Yoko Hamada,
• Tomoko Kawasaki-Takasuka and
• Takashi Yamazaki

Beilstein J. Org. Chem. 2017, 13, 1507–1512, doi:10.3762/bjoc.13.149

• -unsaturated ketones (E)-5 was successfully extended to the transformation of allylic alcohols (E)-6 to saturated ketones 7. Different from the previously reported transition metal-catalyzed protocols by Cahard [8][9][13] and Liu [10][11][12], our transformation nicely proceeded with such a convenient and

Synthesis of novel 13α-estrone derivatives by Sonogashira coupling as potential 17β-HSD1 inhibitors

• Ildikó Bacsa,
• Rebeka Jójárt,
• János Wölfling,
• Gyula Schneider,
• Bianka Edina Herman,
• Mihály Szécsi and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2017, 13, 1303–1309, doi:10.3762/bjoc.13.126

• . There are literature reports about similar transition-metal-catalyzed cyclizations of o-alkynylphenols to construct benzofurans [34][35]. These heterocycles are important structural units in a variety of biologically active natural or synthetic compounds [36][37]. Full hydrogenation of the 2- or 4

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• . What will certainly be interesting in the future if a more in depth mechanism can be discerned. 3.4 Transition metal-catalyzed glycosylation The metal-catalyzed activation of the anomeric center has been employed in carbohydrate chemistry for many decades and continues to be a very rapidly expanding

• this section we highlight some very elegant examples of transition metal-catalyzed glycosylation strategies that have been successful even in the presence of other unprotected hydroxy groups in the molecules. 3.4.1 Au(III)–alkynyl complexation: The Finn group [62] developed a protecting-group-free Au

An eco-compatible strategy for the diversity-oriented synthesis of macrocycles exploiting carbohydrate-derived building blocks

• Sushil K. Maurya and
• Rohit Rana

Beilstein J. Org. Chem. 2017, 13, 1106–1118, doi:10.3762/bjoc.13.110

• transition-metal-catalyzed coupling reactions [19]. Recently, ring-closing alkyne metathesis (RCAM) [20][21] and ring closing metathesis (RCM) [22][23][24][25][26][27][28][29][30][31] have emerged as very powerful tools for macrocyclization including for the preparation of peptidomimetic [17][18][32

α-Acetoxyarone synthesis via iodine-catalyzed and tert-butyl hydroperoxide-mediateded self-intermolecular oxidative coupling of aryl ketones

• Liquan Tan,
• Cui Chen and
• Weibing Liu

Beilstein J. Org. Chem. 2017, 13, 1079–1084, doi:10.3762/bjoc.13.107

• transition-metal-catalyzed direct oxidative coupling reactions of carbonyl compounds with carboxylic acids (or their surrogates) [8][9]. Recently, robust approaches using organohypervalent iodine reagents and peroxide-mediated oxidative coupling have been developed [10][11]. Although impressive progress has

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• building blocks in organic synthesis and final products with interesting biological activities. Over the past decades, substantial progress has been made in transition-metal-catalyzed coupling reactions, which resulted in the emergence of new methods for the synthesis of phenols and aryl thiols. Aryl

• methods for the synthesis of these two important classes of compounds. Herein, we review the recent developments on transition-metal-catalyzed syntheses of phenols from aryl halides and arenes, and aryl thiols from aryl halides. Review 1 Transition-metal-catalyzed synthesis of phenols In early times

• , high temperatures, a narrow substrate scope, low selectivity, and/or low yields. Inspired by the classic Ullmann reaction [15][16], the development of a transition-metal-catalyzed C–O coupling reaction provides various strategies to synthesize C–O-coupled products including ethers and phenols. On the

Effect of the ortho-hydroxy group of salicylaldehyde in the A³ coupling reaction: A metal-catalyst-free synthesis of propargylamine

• Sujit Ghosh,
• Kinkar Biswas,
• Suchandra Bhattacharya,
• Pranab Ghosh and
• Basudeb Basu

Beilstein J. Org. Chem. 2017, 13, 552–557, doi:10.3762/bjoc.13.53

• known as A3 coupling reaction, remains the most common and straightforward method for the synthesis of propargylamine. The A3 coupling reaction is reported under transition-metal-catalyzed conditions using copper [12][17][18][19], gold [17][20][21], silver [17][22], zinc [17][23], nickel [24], iron [25

The reductive decyanation reaction: an overview and recent developments

• Jean-Marc R. Mattalia

Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30

• charge on the carbon adjacent to the cyano group [76][77]. Transition-metal-catalyzed reductive decyanation Hydrogenation of α-aminonitriles The decyanation of α-aminonitriles with hydrogen present in an excess of Raney nickel was described by Husson and co-workers on oxazolidine derivatives [83][84

• on transition-metal-catalyzed reactions focuses on selected examples that show the wide scope of reduced substrates including alkyl cyanides, challenging substrates due to their propensity to undergo β-hydride elimination from alkylmetal intermediates. Nakazawa et al. reported the photoinduced C–CN

• [9], new and convenient synthetic methods have now emerged. Classical metal dissolving conditions are still used but the method, while it works, shows that the course of the reaction may strongly depend on reaction conditions. The transition-metal-catalyzed defunctionalization reactions cover a wide