Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• all atoms of the starting material are found in the product, and thus fulfil an important requirement of “green chemistry” [31]. However, a different Pt(II)-catalysed reaction cascade was observed for 4c, with adamantyl groups at the alkynes. Here, the annulation step is followed by a C–H bond

Regioselective (thio)carbamoylation of 2,7-di-tert-butylpyrene at the 1-position with iso(thio)cyanates

• Anna Wrona-Piotrowicz,
• Marzena Witalewska,
• Janusz Zakrzewski and
• Anna Makal

Beilstein J. Org. Chem. 2017, 13, 1032–1038, doi:10.3762/bjoc.13.102

• syntheses of various products (especially heterocycles) [21][22]. Furthermore, aromatic amides undergo a variety of directed C–H bond functionalizations [23]. Herein we report that the reaction of 2 with aliphatic isocyanates and isothiocyanates proceeds regioselectively at the 1-position (Scheme 1

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

• investigation revealed that HFIP participated in the catalytic cycle before the activation of C–H bond. 1.2.2.2 Carboxylic acid, ketone and their derivatives as directing groups: In 2009, the Yu group used Pd(OAc)2 and accomplished the direct ortho-hydroxylation of benzoic acid [69]. Their developed protocol

• hydroxylation of arenes: In 2012, Ackermann and co-workers used [Ru(O2CMes)2(p-cymene)] as catalyst to achieve the C–H bond oxygenation of N-substituted benzamides in TFA/TFAA. The reaction proceeded in the presence of PhI(OAc)2 as oxidant at 120 °C (Scheme 46) [75]. A broad scope of functional groups could be

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

• removal of a beneficial functional group. The electron-withdrawing properties of the nitrile functional group appear beneficial in a variety of reactions [1][2]. This group coordinates metal complexes and can be used as a directing group for C–H bond activation reactions catalyzed by transition metals [3

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• evidence for two hydrogen bonds formed between the halide or bromide anion and C–H2/C–Hc bonds of another cation L13. Mixed N–H/C–H hydrogen bond donors as organocatalysts The involvement of the ortho C–H bond in the binding event with Lewis-basic sites was proposed by Etter in the late 1980s and later

Direct arylation catalysis with chloro[8-(dimesitylboryl)quinoline-κN]copper(I)

• Sem Raj Tamang and
• James D. Hoefelmeyer

Beilstein J. Org. Chem. 2016, 12, 2757–2762, doi:10.3762/bjoc.12.272

• addition/reductive elimination. The scope of reactivity, including functional group tolerance on the reactants, types of C–H bonds that can be activated, selectivity of C–H bond activation, further optimization studies, and new catalyst design will be topics for further study. The initial results are very

Copper-catalyzed asymmetric sp³ C–H arylation of tetrahydroisoquinoline mediated by a visible light photoredox catalyst

• Pierre Querard,
• Inna Perepichka,
• Eli Zysman-Colman and
• Chao-Jun Li

Beilstein J. Org. Chem. 2016, 12, 2636–2643, doi:10.3762/bjoc.12.260

• process despite the advances that have been made in this field [1]. The directing group strategies are widely used and developed to achieve enantioselective metal-catalyzed C–H bond functionalizations in recent years. Unactivated alkyl C–H bond activation (i.e., without any directing group) is of great

• allow us to design a visible-light-mediated photoredox asymmetric arylation of tetrahydroisoquinolines (THIQs) [15][16][17][18][19][20]. During the last decade, numerous examples of sp3 C–H bond arylation procedures have been developed [1][21][22][23][24][25][26][27][28][29]. In 2008, our group

Radical polymerization by a supramolecular catalyst: cyclodextrin with a RAFT reagent

• Kohei Koyanagi,
• Yoshinori Takashima,
• Takashi Nakamura,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2016, 12, 2495–2502, doi:10.3762/bjoc.12.244

• , including hydrolysis reactions [10][11][12][13][14][15], C–H bond activation [34][35][36], olefin epoxidation [37][38][39], Diels–Alder reactions [40][41][42], 1,3-dipole cycloadditions [43][44], and polymerizations [45][46][47], among others. Selective substrate recognition and activation are essential

Regiocontroled Pd-catalysed C5-arylation of 3-substituted thiophene derivatives using a bromo-substituent as blocking group

• Mariem Brahim,
• Hamed Ben Ammar,
• Jean-François Soulé and
• Henri Doucet

Beilstein J. Org. Chem. 2016, 12, 2197–2203, doi:10.3762/bjoc.12.210

• “green” access to arylated thiophene derivatives as it reduces the number of steps to prepare these compounds and also the formation of wastes. Keywords: aryl bromides; C–H bond activation; catalysis; direct arylation; palladium; thiophenes; Introduction Thiophene derivatives bearing aryl substituents

Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes

• Michael Nonnenmacher,
• Dominik M. Buck and
• Doris Kunz

Beilstein J. Org. Chem. 2016, 12, 1884–1896, doi:10.3762/bjoc.12.178

• -donor character (deduced directly from the larger 1JCH coupling constant of the respective imidazolium salts that correlates with the higher s-character in the C–H bond). Therefore, we expected the average CO stretching frequencies to lie about 15 cm−1 higher at around 2050 cm−1 for complexes 2a and 2b

Cp₂TiCl/D₂O/Mn, a formidable reagent for the deuteration of organic compounds

• Antonio Rosales and
• Ignacio Rodríguez-García

Beilstein J. Org. Chem. 2016, 12, 1585–1589, doi:10.3762/bjoc.12.154

• for both species, which in turn, is dependent upon the zero point for the vibrational energy of both isotopic molecules. As the mass of deuterium is about twice the mass of hydrogen there is a larger activation energy for the C–D bond dissociation than for the C–H bond [4]. The KIE observed allows

Reactivity studies of pincer bis-protic N-heterocyclic carbene complexes of platinum and palladium under basic conditions

• David C. Marelius,
• Curtis E. Moore,
• Arnold L. Rheingold and
• Douglas B. Grotjahn

Beilstein J. Org. Chem. 2016, 12, 1334–1339, doi:10.3762/bjoc.12.126

• and of the C–H bond of acetylene. The same ligand in CpRu complexes 2 and 3 showed heterolysis of dihydrogen [13]. 1 had a much faster ligand exchange rate after ionization as compared to the Cp*Ir analog (ethylene bound in 5 min at rt (CpRu) instead of 16 h at 70 °C (Cp*Ir)). Species 1 could be

Synthesis of 2-substituted tetraphenylenes via transition-metal-catalyzed derivatization of tetraphenylene

• Shulei Pan,
• Hang Jiang,
• Yanghui Zhang,
• Yu Zhang and
• Dushen Chen

Beilstein J. Org. Chem. 2016, 12, 1302–1308, doi:10.3762/bjoc.12.122

• into other functionalities [58][59]. The Larock group reported a novel Pd-catalyzed addition of nitriles to an arene C–H bond for the synthesis of aryl ketones [60][61]. Following the Larock’s conditions, we investigated the carbonylation of tetraphenylene (1) and the carbonylated product 5a was

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• ). Insertion into the C–H bond of 65 provides intermediate 70, which then undergoes migratory insertion into acrylate 66 to give 71. β-Hydride elimination to give the α,β-disubstituted acrylate 72 followed by enantioselective hydride transfer generates the chiral tertiary center in 73. Finally

Synthesis of β-arylated alkylamides via Pd-catalyzed one-pot installation of a directing group and C(sp³)–H arylation

• Yunyun Liu,
• Yi Zhang,
• Xiaoji Cao and
• Jie-Ping Wan

Beilstein J. Org. Chem. 2016, 12, 1122–1126, doi:10.3762/bjoc.12.108

• .12.108 Abstract The synthesis of β-arylated alkylamides via alkyl C–H bond arylation has been realized by means of direct one-pot reactions of acyl chlorides, aryl iodides and 8-aminoquinoline. Depending on the structure of the starting materials, both single and double β-arylated alkylamides could be

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• transformations. Three approaches (Figure 1) have generally been employed to enhance the reactivity and promote the key metalation/C–H bond cleavage step: (1) tuning of the reaction conditions through inclusion of various additives such as metal salts [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18

• [72][73][74][75][76][77][78][79]. Literature studies have suggested that certain anionic ligands on palladium, such as acetate or carbonate, may assist C–H bond cleavage by acting as internal bases as part of a concerted metalation–deprotonation (CMD) pathway, particularly in the case of less electron

• Although aromatic C–H bond activation through palladacycle [214] generation is a critical step in the ortho-directed, activation/cross-coupling sequence, many of its specific mechanistic features are still controversial. Previous studies with arylureas [73][206][215] have formulated a palladacycle as the

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• Recently, iridium has emerged as a powerful catalyst for C–H bond functionalization [20][21][22][23]. In 2014, Yamamoto and co-workers reported a cationic iridium complex catalyzed asymmetric intramolecular hydroarylation of α-ketoamides, yielding 3-substituted 3-hydroxy-2-oxindoles with high

• plausible catalytic cycle was proposed as shown in Scheme 8: [Ir(cod)2](BArF4) and the ligand L4 formed the [Ir] precatalyst in situ, which then activated a C–H bond of the substrate to generate aryl–iridium complex A. Subsequent intramolecular asymmetric hydroarylation of intermediate B produced iridium

The synthesis of functionalized bridged polycycles via C–H bond insertion

• Jiun-Le Shih,
• Po-An Chen and
• Jeremy A. May

Beilstein J. Org. Chem. 2016, 12, 985–999, doi:10.3762/bjoc.12.97

• via C–H bond insertion by carbenes and nitrenes. Applications to natural product synthesis, a description of the essential elements in substrate-controlled reactions, and mechanistic details of transformations are presented. Overall, these transformations allow the construction of important ring

• systems rapidly and efficiently, though additional catalyst development is needed. Keywords: bridged rings; carbene; cascade reaction; C–H bond insertion; nitrene; Introduction Bridged polycyclic natural products are an inviting challenge to the synthetic chemist for their rich display of functional

• access to multiple targets from a single intermediate produced on large scale that may be stored until needed [17]. The C–H bond insertion has great potential as a method to access different polycyclic isomers (e.g., 1 or 3) through C–C or C–N bond formation from a carbene or nitrene, respectively

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• being necessary for catalyst activity (Figure 4a) [87][88][89]. In 2010 Zhong proposed that the presence of the ortho C–H bond of the aryl group could be the key for success because it could participate together with the thiourea function in the activation of the electrophile [90]. This proposal was in

Recent advances in C(sp³)–H bond functionalization via metal–carbene insertions

• Bo Wang,
• Di Qiu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78

• development of intermolecular C–H insertion in the application of C(sp3)–H bond functionalizations, especially for light alkanes, is reviewed. The challenging problem of regioselectivity in C–H bond insertions has been tackled by the use of sterically bulky metal catalysts, such as metal porphyrins and silver

• (I) complexes. In some cases, high regioselectivity and enantioselectivity have been achieved in the C–H bond insertion of small alkanes. This review highlights the most recent accomplishments in this field. Keywords: alkane; diazo compounds; C–H bond functionalization; C–H bond insertion; metal

• has witnessed some exciting advances along this line. Thus, it would be an appropriate time to summarize the field in connection with direct C–H bond functionalization. Since catalytic metal–carbene C(sp3)–H bond insertions have been discussed in a series of excellent reviews [1][2][3][4][5][6][7][8

Opportunities and challenges for direct C–H functionalization of piperazines

• Zhishi Ye,
• Kristen E. Gettys and
• Mingji Dai

Beilstein J. Org. Chem. 2016, 12, 702–715, doi:10.3762/bjoc.12.70

• , path b). Although there have been major advancements made in the field of direct sp3 C–H bond activation and functionalization adjacent to nitrogen in saturated N-heterocycles and acyclic amines [25][26][27], C–H functionalization of piperazines has been a daunting challenge. In comparison to the well

• -studied pyrrolidine and piperidine systems, the existence of the second ring-bound nitrogen in piperazines either causes various side reactions or inhibits or diminishes the reactivity of the C–H bond. This review summarizes the current status and challenges of direct C–H bond functionalization of

• . Transition-metal-catalyzed α-C–H functionalization Transition-metal-catalyzed direct sp3 C–H bond functionalization at the α-carbon of both cyclic and acyclic amines have been a fertile research field [45][46][47]. In the case of saturated N-heterocycles however, most of the efforts have been focused on

Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones

• Ping Qian,
• Bingnan Du,
• Wei Jiao,
• Haibo Mei,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32

• )-diones in good yield. Keywords: C(sp3)–H bond functionalization; cyclization; dihydroisoquinolin-1(2H)-one; N-allylbenzamides; oxidation; Introduction The direct and selective functionalization of an unactivated sp3 C–H bond, which belongs to an effective strategic approach in green and sustainable

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• copper catalysis is in the C–N bond formation by using carbon sources and nitrogen functional groups such as amides. In this review, the recent progress in the amidation reactions employing copper-catalyzed C–H amidation is summarized. Keywords: amidation; C–H bond; cascade reactions; Copper catalysis

• nucleophilic N-alkylation of amides by using pre-functionalized electrophiles such as alkyl halides, alcohols or amines [36][37][38][39][40][41]. An alternative tactic which employs raw C–H bond conversion represents a revolutionary step in the synthesis of N-alkylamides. In 2007, Fu and co-workers [42

• ] reported the copper-catalyzed, tert-butyl hydroperoxide (TBHP)-assisted C–H amidation of tertiary amines 1. By heating at 80 °C, the C–H bond in dimethylaniline underwent direct amidation to provide products 3 in the presence of amides 2. On the other hand, the dephenylation transformation via C–C bond

C–H bond halogenation catalyzed or mediated by copper: an overview

• Wenyan Hao and
• Yunyun Liu

Beilstein J. Org. Chem. 2015, 11, 2132–2144, doi:10.3762/bjoc.11.230

• via direct C–H bond transformation is reviewed. Keywords: C(sp2)–H bond; C(sp3)–H bond; copper; halogenation; Introduction Organohalides are inarguably a class of most useful chemicals owing to their prevalent application in the synthesis of organic products. The versatile reactivity of C–X bonds

• application in C–H bond functionalizations in recent years owing to their distinct advantages such as low cost, high stability and flexible forms of presence [29][30][31]. In the area of C–H bond halogenation, the copper catalysis also constitutes a major practical option. To show the power of copper

• catalysis in modern organic synthesis, herein, we would like to highlight the recent progress in the C–H bond halogenation with copper catalysis or mediation. Review Copper-catalyzed/mediated halogenation of the C(sp2)–H bond Halogenation of the arene C(sp2)–H bond In the synthesis of aryl halides employing

Copper-mediated synthesis of N-alkenyl-α,β-unsaturated nitrones and their conversion to tri- and tetrasubstituted pyridines

• Dimitra Kontokosta,
• Daniel S. Mueller,
• Dong-Liang Mo,
• Wiktoria H. Pace,
• Rachel A. Simpson and
• Laura L. Anderson

Beilstein J. Org. Chem. 2015, 11, 2097–2104, doi:10.3762/bjoc.11.226

• ][38], fragment couplings [39][40][41][42], and transition metal-catalyzed C–H bond functionalization of α,β-unsaturated imines and oximes [43][44][45][46][47][48][49][50]. We were inspired by the copper-catalyzed coupling of protected α,β-unsaturated oximes and alkenylboronic acids developed by

• corresponding tri- and tetrasubstituted pyridines 9 (Scheme 2C). This use of α,β-unsaturated oxime reagents for the synthesis of pyridines is unique from transition metal-catalyzed C–H bond functionalization processes that require a regioselective migratory insertion. This route is appealing due to the