Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• adopting SM coupling and RCM as key steps. In this respect, SM coupling of sulfoximine 65 with potassium vinyltrifluoroborate (66) in the presence of a palladium catalyst produced vinyl sulfoximine derivative 67 (73%). Next, N-alkenylation of sulfoximine 67 was accomplished with Z-vinyl bromide (68) to

A challenging redox neutral Cp*Co(III)-catalysed alkylation of acetanilides with 3-buten-2-one: synthesis and key insights into the mechanism through DFT calculations

• Andrew Kenny,
• Alba Pisarello,
• Arron Bird,
• Paula G. Chirila,
• Alex Hamilton and
• Christopher J. Whiteoak

Beilstein J. Org. Chem. 2018, 14, 2366–2374, doi:10.3762/bjoc.14.212

• optimisation led to the inclusion of an increased catalyst loading (20 mol %) and change of solvent/base, which resulted in a synthetically useful yield of the coupling product 2a (58%; Scheme 2b). This need for increased catalyst loading was also previously reported by Kanai and Matsunaga for the alkenylation

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• limited to terminal alkynes. Additionally, they applied this methodology to design a mitochondria-targeted imaging dye from electron-withdrawing formyl-substituted indoles and alkynes. Later, Maji’s group reported an N-tert-butyl amide-directed mono- and di-alkenylation reactions using a cobalt catalyst

• )-catalyzed hydroarylation of terminal alkynes with arenes. Co(III)-catalyzed hydroarylation of alkynes with amides. Co(III)-catalyzed C–H alkenylation of arenes. Co-catalyzed alkylation of substituted benzamides with alkenes. Co-catalyzed switchable hydroarylation of styrenes with 2-aryl pyridines. Co

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

• groups into the ortho position of functionalized arenes has attracted significant attention because of the synthetic versatility of alkenyl groups. The C–H alkenylation has been achieved most extensively by way of the dehydrogenative Heck-type reaction of olefins [7][8][9]. Meanwhile, the hydroarylation

• of alkynes has also been explored as an alternative approach for C–H alkenylation [10]. Despite the significant progress made, each of these C–H alkenylation manifolds has some critical limitations. For example, the dehydrogenative Heck reaction is often limited to activated monosubstituted alkenes

Reagent-controlled regiodivergent intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and β-ketoamides

• Irwan Iskandar Roslan,
• Kian-Hong Ng,
• Gaik-Khuan Chuah and
• Stephan Jaenicke

Beilstein J. Org. Chem. 2017, 13, 2739–2750, doi:10.3762/bjoc.13.270

• traditional Pd-catalyzed aryl–heteroaryl coupling to biaryls [57]. Since then, KOt-Bu has been used as a mediator for various reactions including aryl–aryl coupling [58][59][60][61][62][63], inter- and intramolecular cyclizations [64][65][66][67][68], amidation [69], alkenylation [70], oxidation [71] and

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins

• Alexei N. Kiselev,
• Olga K. Grigorova,
• Alexei D. Averin,
• Sergei A. Syrbu,
• Oskar I. Koifman and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2017, 13, 1524–1532, doi:10.3762/bjoc.13.152

• ][11], Suzuki–Miyaura [12][13][14][15] and Stille couplings [16][17][18][19][20][21][22] were successfully applied for this purpose. Direct arylation and alkenylation are modern approaches for the formation of C–C bonds, and the application of these methodologies to porphyrins was widely studied by

Chromium(II)-catalyzed enantioselective arylation of ketones

• Gang Wang,
• Shutao Sun,
• Ying Mao,
• Zhiyu Xie and
• Lei Liu

Beilstein J. Org. Chem. 2016, 12, 2771–2775, doi:10.3762/bjoc.12.275

• addition reactions mainly focused on allylation, propargylation, alkenylation and alkylation of aldehydes [10][11]. Since the first example of enantioselective allylation of aldehydes catalyzed by a Cr(II)–salen complex in 1999 by Cozzi and co-workers [12], several elegant catalytic enantioselective

• allylation and propargylation reactions have been developed by the groups of Nakada [13][14], Berkessel [15], Kishi [16], Sigman [17], Yamamoto [18], Guiry [19], Chen [20], Gade [21], White [22], and Zhang [23][24][25], respectively. The alkenylation and alkylation reactions were mainly explored by the Kishi

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

• previously mentioned, a drawback characteristic of several ortho-directed C–H activation cross-coupling approaches has been the undesired coupling at both sites ortho- to the directing group. These new conditions completely inhibited second-stage alkenylation, thereby generating singly derivatized arylureas

Reactions of N,3-diarylpropiolamides with arenes under superelectrophilic activation: synthesis of 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones and their derivatives

• Larisa Yu. Gurskaya,
• Diana S. Belyanskaya,
• Dmitry S. Ryabukhin,
• Denis I. Nilov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 950–956, doi:10.3762/bjoc.12.93

• dications can either undergo an intramolecular cyclization to 4-arylquinolin-2(1H)-ones 3 or, alternatively, react with arenes as external π-nucleophiles. In this latter pathway, Friedel–Crafts alkenylation of arenes by species A leads to structures 4, which can then be diprotonated to the cations B and

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

• [18][19], decarboxylative alkenylation of cycloalkanes with aryl vinylic carboxylic acids [20][21], trifluoromethylthiolation [22], thiolation [23][24], alkenylation [25][26], dehydrogenation−olefination and esterification [27][28], radical addition/1,2-aryl migration [29], cascade alkylation

Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems

• Kirk W. Shimkin and
• Donald A. Watson

Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248

• alkenes and alkynes One of the burgeoning areas of copper-catalyzed cross-coupling chemistry is the alkenylation of alkyl halide substrates. This transformation is achieved via formation of a transient radical, addition to a π-system (an alkene or an alkyne), followed by elimination or reincorporation of

• a halide atom. This general scheme is outlined in Scheme 8. In 2013, Nishikata and co-workers reported that a copper/amine catalyst system catalyzes the alkenylation of tertiary alkyl bromides bearing an electron-withdrawing group [32]. As with many ATR reactions, multi-dentate amines were critical

• the observed product (Scheme 9). While the reaction conditions are similar to those utilized in atom transfer radical addition and polymerization reactions, the use of excess amine was critical for a robust alkenylation reaction and to avoid atom transfer and polymerization products. Various electron

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

• -catalyzed C–H activation. Based on the known results of quinoline N-oxide C–H alkenylation [61], arylation [62] and alkylation [63] etc, Li and co-workers [64] investigated and established the C–H amidation of quinoline N-oxides 52 via copper catalysis. According their results, quinoline N-oxides 51

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• using catalysts 1 and 2 [32]. The tetraallyl derivative, prepared from 142 by an allylation protocol, was subjected to a RRM sequence in the presence of the catalyst 1 to produce propellane derivative 144 containing an oxa-bowl moiety. In another sequence [33], the alkenylation of sulfone 145 gave the

Design and synthesis of polycyclic sulfones via Diels–Alder reaction and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha and
• Rama Gunta

Beilstein J. Org. Chem. 2015, 11, 1373–1378, doi:10.3762/bjoc.11.148

• . Interestingly the starting materials used are simple and commercially available. Keywords: alkenylation; Diels–Alder reaction; ring-rearrangement metathesis; sulfones; Introduction Sulfones [1][2][3][4][5][6][7][8] are popular building blocks [9] in organic synthesis. They are also useful substrates for the

• in cis-arrangement with each other [35][36][37]. Analogously, the alkenylation of sulfone 6 was optimized with other electrophiles and the results are summarized in Table 2 (entries 2–4). In this regard, sulfone 6 was butenylated with 4-bromo-1-butene and n-BuLi in the presence of HMPA at −74 °C to

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• ]. These observations led Hayashi, Hiyama and co-workers to develop mild conditions for the rhodium-catalyzed asymmetric 1,4-arylation and alkenylation [155]. They employed a series of organo[2-(hydroxymethyl)phenyl]dimethylsilanes [156][157][158] as organosilicon reagents and they also used these

P(O)R₂-directed Pd-catalyzed C–H functionalization of biaryl derivatives to synthesize chiral phosphorous ligands

• Rong-Bin Hu,
• Hong-Li Wang,
• Hong-Yu Zhang,
• Heng Zhang,
• Yan-Na Ma and
• Shang-dong Yang

Beilstein J. Org. Chem. 2014, 10, 2071–2076, doi:10.3762/bjoc.10.215

• , alkenylation, the P(O)(iPr)2 group showed a good guiding ability, but the corresponding substrates could not be obtained because the phosphate moiety did not react with the (iPr)MgBr. Under the optimized conditions, we started to investigate the scope and applicability of our strategies. Initially, we used

• chiral [1,1'-binaphthalen]-2-yldiphenylphosphine oxide as a substrate [35]. In the process of alkenylation and acetoxylation, the corresponding products 2a and 2b were obtained in moderate yields and high enantioselectivities. Next, we examined the substituent effect with P(O)(p-Tol)2 as a directing

• group: The reactions of alkenylation, acetoxylation, hydroxylation and acylation occurred smoothly. Even if the products were obtained in low to moderate yields, they were optically pure (Figure 1, 2c–f). For the substrate of 4-methoxy substituted binaphthyl, we could achieve the alkenylation product 2g

Rational design of cyclopropane-based chiral PHOX ligands for intermolecular asymmetric Heck reaction

• Marina Rubina,
• William M. Sherrill,
• Alexey Yu. Barkov and
• Michael Rubin

Beilstein J. Org. Chem. 2014, 10, 1536–1548, doi:10.3762/bjoc.10.158

• Guiry [57][58] (Figure 2) were employed in the asymmetric Heck reaction of different cyclic olefins. Furthermore, Gilbertson demonstrated PHOX ligands featuring apobornene backbone (Figure 2) exhibit outstanding activities and selectivities in the arylation and alkenylation of different cyclic

Consecutive cross-coupling reactions of 2,2-difluoro-1-iodoethenyl tosylate with boronic acids: efficient synthesis of 1,1-diaryl-2,2-difluoroethenes

• Ju Hee Kim,
• Su Jeong Choi and
• In Howa Jeong

Beilstein J. Org. Chem. 2013, 9, 2470–2475, doi:10.3762/bjoc.9.286

• of 2 with arylboronic acids prompted us to examine similar coupling reactions with alkenylboronic acids. The same reaction conditions of the mono-coupling reaction of 2 with arylboronic acid was applied to the alkenylation of 2. Therefore, the cross-coupling reaction of 2 with trans-2

AgOTf-catalyzed one-pot reactions of 2-alkynylbenzaldoximes with α,β-unsaturated carbonyl compounds

• Qiuping Ding,
• Dan Wang,
• Puying Luo,
• Meiling Liu,
• Shouzhi Pu and
• Liyun Zhou

Beilstein J. Org. Chem. 2013, 9, 1949–1956, doi:10.3762/bjoc.9.231

• ). This observation indicated that the Palladium-catalyzed alkenylation reaction mechanism might be similar to that described by Cui and Wu [46]. Conclusion In summary, we have demonstrated that one-pot reactions of 2-alkynylbenzaldoximes with α,β-unsaturated carbonyl compounds catalyzed by AgOTf occur

• File 1. Proposed route for the AgOTf-catalyzed one-pot reaction of 2-alkynylbenzaldoxime with an α,β-unsaturated carbonyl compound. Synthesis of 1-alkylated isoquinoline 3a by a AgOTf-catalyzed one-pot reaction in different solvents. Pd-catalyzed one-pot alkenylation reaction of 2-alkynylbenzaldoxime

Iron-catalyzed decarboxylative alkenylation of cycloalkanes with arylvinyl carboxylic acids via a radical process

• Jincan Zhao,
• Hong Fang,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2013, 9, 1718–1723, doi:10.3762/bjoc.9.197

• excellent stereoselectivity, and only trans-isomers are obtained. Keywords: alkenylation; cycloalkanes; decarboxylative; Fe(acac)3; free radical; sp3 C–H bonds; Introduction Direct C–H functionalization has become one of the most useful and attractive tools in organic chemistry because it can construct

• alkenylation of cycloalkanes with high selectivity and stereospecificity remains a great challenge and attracted a lot of attention in the past years. In 1996, the Fuchs group described the alkenylation of cyclohexane by a radical reaction with vinyl triflone [58]. In 2003, the Yao group reported that styryl

• ][68]. Our group was surprised to find that low-cost Fe(acac)3 could catalyze the direct alkenylation of cyclohexane sp3 C–H bonds by decarboxylative couplings with high efficiency. Results and Discussion We initiated our investigation by reacting cinnamic acid (1a, 0.3 mmol) with cyclohexane (2a, 2 mL

Direct alkenylation of indolin-2-ones by 6-aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles: a novel approach

• Sandeep Kumar,
• Ramendra Pratap,
• Abhinav Kumar,
• Brijesh Kumar,
• Vishnu K. Tandon and
• Vishnu Ji Ram

Beilstein J. Org. Chem. 2013, 9, 809–817, doi:10.3762/bjoc.9.92

• , Lucknow-226001, India 10.3762/bjoc.9.92 Abstract A direct one-pot base-induced alkenylation of indolin-2-ones has been developed by using 6-aryl-4-methylthio-2H-pyran-2-one-3-carbonitriles. Different bases such as MeONa, NaH and t-BuONa have been used to optimize the reaction conditions to obtain the

• desired product. NaH in THF was found to be the most suitable for the alkenylation of indolin-2-ones. Reaction in the presence of other bases led to the formation of 1-aryl-3-methoxy/methylthio-5H-dibenzo[d,f][1,3]diazepin-6(7H)-ones. Quantum chemical calculations have been performed to explain the nature

• of the weak noncovalent interactions operating in the supramolecular architectures of alkenylated indoline-2-ones and to explain the relative stability of one of the tautomers with respect to the others. Keywords: alkenylation; dibenzo[d,f][1,3]diazepin-6(7H)-one; indolin-2-one; ketene dithioacetal

Titanium-mediated reductive cross-coupling reactions of imines with terminal alkynes: An efficient route for the synthesis of stereodefined allylic amines

• Kebin Mao,
• Guoqin Fan,
• Yuanhong Liu,
• Shi Li,
• Xu You and
• Dan Liu

Beilstein J. Org. Chem. 2013, 9, 621–627, doi:10.3762/bjoc.9.69

• ], iodocyclocarbamates [19] and isoxazolines [20]. Although it has been reported that allylic amines can be synthesized by methods such as amination of allylic alcohols [21][22][23][24], direct allylic amination of simple alkenes [25][26][27], Morita–Baylis–Hillman reaction [28], alkenylation of imines [29][30][31][32

Iron-containing mesoporous aluminosilicate catalyzed direct alkenylation of phenols: Facile synthesis of 1,1-diarylalkenes

• Satyajit Haldar and
• Subratanath Koner

Beilstein J. Org. Chem. 2013, 9, 49–55, doi:10.3762/bjoc.9.6

• reagents to afford 1,1-disubstituted olefins [27]. Alternatively, Friedel–Crafts-type alkenylation could be a better choice to prepare such regiospecific vinyl aromatic compounds. Yamaguchi et al. reported a direct ortho alkenylation of phenols with 1-alkynes using SnCl4 and Bu3N in acetonitrile under

• reflux [28]. Further developments include the metal trifluoromethanesulfonate-catalyzed Friedel–Crafts alkenylation of arenes using alkynes by Tsuchimoto et al. [29] and the addition of simple arenes to arylacetylenes to afford exclusive 1,1-diarylethylenes through a C–C coupling reaction catalyzed by a

• conditions”. On further exploration of the use of iron-based mesoporous aluminosilicate catalyst in the direct alkenylation of arenes, we have succeeded in vinylation of various phenols with different phenylacetylenes. In this paper we report a convenient method for the alkenylation of phenols with aryl