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

• -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

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

Eosin Y-catalyzed visible-light-mediated aerobic oxidative cyclization of N,N-dimethylanilines with maleimides

• Zhongwei Liang,
• Song Xu,
• Wenyan Tian and
• Ronghua Zhang

Beilstein J. Org. Chem. 2015, 11, 425–430, doi:10.3762/bjoc.11.48

• as a photocatalyst has been developed. The metal-free protocol involves aerobic oxidative cyclization via sp3 C–H bond functionalization process to afford good yields in a one-pot procedure under mild conditions. Keywords: aerobic oxidative cyclization; C–H functionalization; Eosin Y; photoredox

• , inexpensive, and have great potential for applications in visible-light-mediated photoredox reactions [19][20][21][22][23][24][25][26][27]. More recently, visible-light-induced sp3 C–H bond functionalization adjacent to nitrogen atoms has been extensively studied and has become a fundamental organic

• the area of visible light photoredox reactions. Visible-light-induced sp3 C–H bond functionalization of tertiary amines. Substrate scope for aerobic oxidative cyclization of N,N-dimethylanilines with maleimides. A proposed reaction mechanism. Screening and control experimentsa. Optimization of

Hindered aryl bromides for regioselective palladium-catalysed direct arylation at less favourable C5-carbon of 3-substituted thiophenes

• Rongwei Jin,
• Charles Beromeo Bheeter and
• Henri Doucet

Beilstein J. Org. Chem. 2014, 10, 1239–1245, doi:10.3762/bjoc.10.123

• desired 5-arylation products in moderate to good yields using only 0.5 mol % of a phosphine-free and air-stable palladium catalyst. Then, from these 5-arylthiophenes, a second palladium-catalysed C–H bond functionalization at C2 of the thiophene ring allows the synthesis of 2,5-diarylthiophenes with two

Alkyne hydroarylation with Au N-heterocyclic carbene catalysts

• Cristina Tubaro,
• Marco Baron,
• Andrea Biffis and
• Marino Basato

Beilstein J. Org. Chem. 2013, 9, 246–253, doi:10.3762/bjoc.9.29

• ; gold; hydroarylation; N-heterocyclic carbenes; Introduction The hydroarylation of alkynes (Scheme 1) is arguably one of the most intensively studied reactions leading to aromatic C–H bond functionalization [1][2][3][4][5][6][7]. In this reaction, the C–H bond of an arene adds formally trans to the

Copper-catalyzed CuAAC/intramolecular C–H arylation sequence: Synthesis of annulated 1,2,3-triazoles

• Rajkumar Jeyachandran,
• Harish Kumar Potukuchi and
• Lutz Ackermann

Beilstein J. Org. Chem. 2012, 8, 1771–1777, doi:10.3762/bjoc.8.202

• 3a (Table 1). Notably, the envisioned C–H bond functionalization occurred readily with the aryl iodide 3a when catalytic amounts of CuI were used, even at a reaction temperature as low as 60 °C, with optimal yields being obtained at 80 °C (Table 1, entries 1–6). While the transformation proceeded

Extending the utility of [Pd(NHC)(cinnamyl)Cl] precatalysts: Direct arylation of heterocycles

• Anthony R. Martin,
• Anthony Chartoire,
• Alexandra M. Z. Slawin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2012, 8, 1637–1643, doi:10.3762/bjoc.8.187

• . Keywords: C–H functionalization; direct arylation; heterocycles; N-heterocyclic carbenes; palladium; Introduction As a powerful addition to the classic palladium cross-coupling reactions, C–H bond functionalization has become a growing field of research over the last few years. The ubiquity of C–H bonds

• catalytic systems, and in the end to see whether the reactivity and application scope of these commercially available complexes could be broadened to include C–H bond functionalization transformations. We now report the activity of the [Pd(NHC)(cin)Cl] complexes 1–4 in the direct arylation of heterocycles

• utilised in various cross-coupling and, now, C–H-bond-functionalization reactions. Experimental General procedure for the direct arylation of heterocycles In a glovebox, a vial containing a stirring bar was charged with K2CO3 (124 mg, 0.9 mmol, 1.5 equiv) and pivalic acid (0.18 mmol, 18 mg, 30 mol %), and

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

Organocatalytic C–H activation reactions

• Subhas Chandra Pan

Beilstein J. Org. Chem. 2012, 8, 1374–1384, doi:10.3762/bjoc.8.159

• formation of C–C and C–X bonds [1][2][3]. The advantage of this method is that it does not require the functional group of the carbon atom, as in the conventional approach. Transition-metal-catalysed C–H bond functionalization reactions have been well-studied and different site-selective (regioselective and

• being one of the “key green chemistry research areas” [4][5][6]. This review describes the current “state of the art” in organocatalyzed C–H activation reactions and highlights recent advances in sp2 and sp3 C–H bond functionalization. For simplicity, iodide or hypervalent iodine-mediated metal-free C–H

Hypervalent iodine(III)-induced methylene acetoxylation of 3-oxo-N-substituted butanamides

• Wei-Bing Liu,
• Cui Chen,
• Qing Zhang and
• Zhi-Bo Zhu

Beilstein J. Org. Chem. 2011, 7, 1436–1440, doi:10.3762/bjoc.7.167

• ][3][4][5][6][7][8][9][10][11][12][13][14]. Indeed, direct oxidative C–H bond functionalization provides an atom-economical and efficient pathway to achieve these goals. Representative examples have been elegantly utilized not only in academic research, but also in the production of a variety of fine

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

• under mild conditions. Toste’s group reported a gold(I)-catalyzed sequential cycloisomerization/sp3 C–H bond functionalization (Scheme 39) of 1,5-enynes 218 and 1,4-enallenes to yield tetracyclododecane 219 and tetracyclotridecane derivatives, respectively [97]. These transformations represent rare

Recent progress on the total synthesis of acetogenins from Annonaceae

• Nianguang Li,
• Zhihao Shi,
• Yuping Tang,
• Jianwei Chen and
• Xiang Li

Beilstein J. Org. Chem. 2008, 4, No. 48, doi:10.3762/bjoc.4.48