One-pot synthesis of 4′-alkyl-4-cyanobiaryls on the basis of the terephthalonitrile dianion and neutral aromatic nitrile cross-coupling

• Roman Yu. Peshkov,
• Elena V. Panteleeva,
• Wang Chunyan,
• Evgeny V. Tretyakov and
• Vitalij D. Shteingarts

Beilstein J. Org. Chem. 2016, 12, 1577–1584, doi:10.3762/bjoc.12.153

• acylation–reduction–halogenation–cyanodehalogenation (Scheme 1) [15], are currently being replaced with methods based on transition-metal-catalyzed biaryl cross-coupling [16][17][18][19][20][21]. This methodology is well developed, compatible with different substituents in the substrate and opens up a new

Selective bromochlorination of a homoallylic alcohol for the total synthesis of (−)-anverene

• Frederick J. Seidl and
• Noah Z. Burns

Beilstein J. Org. Chem. 2016, 12, 1361–1365, doi:10.3762/bjoc.12.129

• homoallylic alcohol. Critical factors for optimization of this reaction are highlighted. The utility of the product bromochloride is demonstrated by the first total synthesis of an antibacterial polyhalogenated monoterpene, (−)-anverene. Keywords: enantioselective catalysis; halogenation; natural products

• halogenation than the same reaction with allylic alcohols. Consistent results were obtained when bromochlorination reactions were run in round-bottomed flasks, using rod-shaped magnetic stir bars roughly the length of the flask radius, and with stirring at no less than 1500 rpm (see Supporting Information File

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

• research on the properties and application of tetraphenylene derivatives. Keywords: acetoxylation; carbonylation; halogenation; tetraphenylene; transition metal; Introduction Tetraphenylene (1) is one of the simplest motifs in the eight-membered ring aromatic compounds (Figure 1) [1][2]. Based on its

• halogenation of tetraphenylene attracted our attention. The Wang group reported an efficient and mild protocol for a gold-catalyzed direct C–H halogenation of arenes with N-halosuccinimides [56][57]. Therefore, we initially investigated the chlorination of tetraphenylene by subjecting it to Wang’s conditions

• that aliphatic nitriles 4j,k were also found to be reactive under the conditions. Conclusion In conclusion, three reactions for halogenation, acetoxylation, and carbonylation of tetraphenylene (1) have been developed via a transition-metal-catalyzed direct derivatization. The reactions provide new

Palladium-catalyzed picolinamide-directed iodination of remote ortho-C−H bonds of arenes: Synthesis of tetrahydroquinolines

• William A. Nack,
• Xinmou Wang,
• Bo Wang,
• Gang He and
• Gong Chen

Beilstein J. Org. Chem. 2016, 12, 1243–1249, doi:10.3762/bjoc.12.119

• and Discussion Methods for metal-catalyzed halogenation of ortho C−H bonds at the more remote ε position are scarce, in contrast to the large number of ortho C−H halogenation reactions of arenes effected by more proximal directing groups [23][24][25][26][27][28][29][30][31][32][33]. Fundamentally, it

• is challenging to achieve efficient reactions through kinetically unfavorable seven-membered palladacycle intermediates. Furthermore, the electrophilic reagents used for C–H halogenation can often react with arenes through undirected SEAr pathways, which need to be suppressed for regioselectivity. To

• address this issue upfront, we commenced our study of Pd-catalyzed ε-C−H halogenation with 3-arylpropylpicolinamide 5 bearing a strongly electron-donating OMe group (Table 1, see Supporting Information File 1 for the preparation of 5). Iodination of 5 under our previous SEAr protocol gave undirected

Iodine-mediated synthesis of 3-acylbenzothiadiazine 1,1-dioxides

• Long-Yi Xi,
• Ruo-Yi Zhang,
• Lei Shi,
• Shan-Yong Chen and
• Xiao-Qi Yu

Beilstein J. Org. Chem. 2016, 12, 1072–1078, doi:10.3762/bjoc.12.101

• ). To shed light on the mechanism of this reaction, a control experiment was conducted. It is known that acetophenones can undergo halogenation and further Kornblum oxidation to give phenylglyoxal in a I2/DMSO system [33][34]. We isolated the product in 85% yield by heating phenylglyoxal and 2a in DMSO

• isolated after stirring 12 h at 80 °C. On the basis of this experiment described above and literature [13][35][36], a possible mechanism was proposed in Scheme 7. The halogenation of 1a with iodine results in the formation of compound A, which, via Kornblum oxidation, provides phenylglyoxal B. The

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

• allowed them to be used as precursors in the construction of natural products, medicinal, functional materials and agricultural chemicals [1][2][3][4][5][6]. Therefore, the research toward catalytic generation of C–X bonds constitutes a significant issue in organic synthesis. Electrophilic halogenation of

• , significant advances have also occurred in the C–H halogenation catalyzed by different transition metals as Pd [19][20][21][22][23], Rh [24][25], Ru [26], Au [27], Co [28], etc. As a class of readily available and ubiquitously employed transition metal catalysts, copper catalysts have exhibited tremendous

Cross-metathesis reaction of α- and β-vinyl C-glycosides with alkenes

• Ivan Šnajdr,
• Kamil Parkan,
• Filip Hessler and
• Martin Kotora

Beilstein J. Org. Chem. 2015, 11, 1392–1397, doi:10.3762/bjoc.11.150

• vinyl β-C-deoxyribofuranoside was based on transformation of 6-O-tert-butyldiphenylsilyl-3,5-dideoxy-5-iodo-L-lyxo-hexofuranose [14]. A reaction sequence relying on Horner–Wadsworth–Emmons/ring closure–halogenation/Ramberg–Bäcklund/Wittig reaction gave rise to the equimolar mixture of styryl α- and β-C

Electrochemical oxidation of cholesterol

• Jacek W. Morzycki and
• Andrzej Sobkowiak

Beilstein J. Org. Chem. 2015, 11, 392–402, doi:10.3762/bjoc.11.45

• affords different products depending on the reaction conditions. Keywords: allylic oxidation; cholesterol; electrochemical halogenation; electrochemical oxidation; Introduction Cholesterol is the most common steroid in the mammalian body. It is necessary to ensure a proper membrane permeability and

Synthesis and biological evaluation of novel N-α-haloacylated homoserine lactones as quorum sensing modulators

• Michail Syrpas,
• Ewout Ruysbergh,
• Christian V. Stevens,
• Norbert De Kimpe and
• Sven Mangelinckx

Beilstein J. Org. Chem. 2014, 10, 2539–2549, doi:10.3762/bjoc.10.265

• . Most of the α-haloacylated analogues did not exhibit a significant reduction when tested in the QS inhibition test. Therefore, these novel analogues could be utilized as chemical probes for QS structure–activity studies. Keywords: halogenated fatty acids; halogenation; N-acylated homoserine lactones

• halogenation itself leads to the deactivation of β-keto AHLs [34]. In summary, it can be suggested that some of these novel halogenated analogues 6, 8 and especially 11 could be utilized as tools in QS research, e.g., with wild type bacteria or other reporter strains because of their partially retained

Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids

• Roman Matthessen,
• Jan Fransaer,
• Koen Binnemans and
• Dirk E. De Vos

Beilstein J. Org. Chem. 2014, 10, 2484–2500, doi:10.3762/bjoc.10.260

• cyanoacetic acid product have similar oxidation potentials. On top of that, some halogenation of the solvent to chloroacetonitrile was observed as a side reaction [147]. This reaction setup was also tested with propionitrile, butyronitrile, benzyl chloride and toluene in the anolyte compartment. Adjacent

Efficient routes toward the synthesis of the D-rhamno-trisaccharide related to the A-band polysaccharide of Pseudomonas aeruginosa

• Aritra Chaudhury,
• Sajal K. Maity and
• Rina Ghosh

Beilstein J. Org. Chem. 2014, 10, 1488–1494, doi:10.3762/bjoc.10.153

• synthesis of monomeric D-rhamnose has been highly streamlined by Roy et al. in 2007 [26], and further improvement on this method was reported by Kiefel et al. in 2011 [27]. However, the deoxygenation protocol involving halogenation under Mitsunobu conditions was found to be inefficient when applied to

Rasta resin–triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions

• Xuanshu Xia and
• Patrick H. Toy

Beilstein J. Org. Chem. 2014, 10, 1397–1405, doi:10.3762/bjoc.10.143

• reagent precursors in a wide range of halogenation reactions. The rasta resin–triphenylphosphine oxides were reacted with either oxalyl chloride or oxalyl bromide to form the corresponding halophosphonium salts, and these in turn were reacted with alcohols, aldehydes, aziridines and epoxides to form

• halogenated products in high yields after simple purification. The polymer-supported triphenylphosphine oxides formed as a byproduct during these reactions could be recovered and reused numerous times with no appreciable decrease in reactivity. Keywords: Appel reaction; halogenation; organophosphorus

• reactions, such as those illustrated in Scheme 2: (1) the conversion of alcohols 4 to alkyl halides 5 (the Appel reaction), (2) the conversion of aldehydes 6 to 1,1-dihaloalkanes 7, (3) halogenation of aziridines 8 to form 2-haloamines 9, (4) halogenation of epoxides 10 to form 1,2-dihaloalkanes 11, (5) and

Stereoselective synthesis of carbocyclic analogues of the nucleoside Q precursor (PreQ₀)

• Sabin Llona-Minguez and
• Simon P. Mackay

Beilstein J. Org. Chem. 2014, 10, 1333–1338, doi:10.3762/bjoc.10.135

• ] (Figure 3). The resulting pivalamide 8 proved to be more soluble than 1 and the subsequent halogenation step was accomplished in the presence of a phase transfer catalyst, affording the desired chloro-intermediate 9 in fair yield. In our hands, nucleophilic aromatic substitution on 9 using amines of

Visible-light photoredox catalysis enabled bromination of phenols and alkenes

• Yating Zhao,
• Zhe Li,
• Chao Yang,
• Run Lin and
• Wujiong Xia

Beilstein J. Org. Chem. 2014, 10, 622–627, doi:10.3762/bjoc.10.53

• phenols. The typical approaches include direct electrophilic halogenation by using molecular bromine or N-bromosuccinimide (NBS) [6][7][8], organometallic catalyst-promoted bromination [9][10][11][12], and the oxidative bromination of phenols [13][14][15]. Nevertheless, most of the methods suffer from

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

α-Bromodiazoacetamides – a new class of diazo compounds for catalyst-free, ambient temperature intramolecular C–H insertion reactions

• Åsmund Kaupang and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2013, 9, 1407–1413, doi:10.3762/bjoc.9.157

• cyclic amide side chains. Keywords: α-halo-β-lactam; diazo; halocarbonylcarbene; halogenation; thermolysis; Introduction Diazocarbonyl compounds are popular precursors for carbonylcarbenes and -carbenoids, the synthetic utility of which is thoroughly established through their successful employment in

• et al. reported the syntheses of an α-halodiazomethyl phosphonic acid dimethyl ester and an α-halodiazomethyl diphenyl phosphoxide, starting from the silver salts of the respective diazo compounds [10]. More recently, two novel protocols for the halogenation of diazoesters and -phosphonates have been

• the halogenation of diazoacetamides. We report herein the bromination of the diazoacetamides derived from a selection of cyclic secondary amines, using DBU and N-bromophthalimide (NBP), as well as an investigation of the ability of the carbenes/carbenoids derived from the resulting α

A new synthetic protocol for coumarin amino acid

• Xinyi Xu,
• Xiaosong Hu and
• Jiangyun Wang

Beilstein J. Org. Chem. 2013, 9, 254–259, doi:10.3762/bjoc.9.30

• , by using the Henderson–Hasselbalch equation. The halogenation of 1a at the 6-position decreases the pKa value, which makes compounds 1b and 1c good substitutes for 1a in fluorescent labeling and other investigations in biological systems. Screening for the synthetase/tRNA pair for 1b and 1c is under

Polar reactions of acyclic conjugated bisallenes

• Reiner Stamm and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 36–48, doi:10.3762/bjoc.9.5

• and epoxides, hydrohalogenation (HCl, HBr addition), halogenation (Br2 and I2 addition), and [2 + 2] cycloaddition with chlorosulfonyl isocyanate. The resulting adducts were fully characterized by spectroscopic and analytical methods; they constitute interesting substrates for further organic

• . Hydrohalogenation and halogenation of acyclic conjugated bisallenes Hydrohalogenation of 2 and 5 The addition of protic acids HX (with X usually being Cl and Br) to allenes has been studied quite carefully. The process usually takes place according to the Markovnikoff rule and often cannot be stopped at the

• postulate a butadienylallene intermediate, 51, again. Halogenation of 2, 3 and 11 Among the addition of halogens the addition of bromine and iodine to various allenes has been particularly well studied [28]. Whereas bromine is added to the more highly substituted double bond of simple monoallenes, iodine

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• (UVC) and are particularly suited to carbonyl and arene photochemistry as well as halogenation chemistry. These lamps are also available with a range of phosphor coatings to emit both UVB and UVA radiation. They have found commercial use in medical, tanning and insect-attraction applications. These

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• same couple PdCl2(MeCN)2/CuX2 as catalyst and oxidant, respectively. 2-Indolylallylcarboxamides 48 have been found to be suitable substrates to access variously substituted β-carbolinones 49 and 50 through alkenylation/halogenation or alkenylation/esterification processes selectively obtained by

• acetonitrile as the solvent, allowed the formation of the dihalogenated pyrazino[1,2-a]indole derivatives 52 by an unusual aminohalogenation/halogenation sequence (Scheme 30). The formation of the 3-haloderivatives XXI, ascribable solely to the action of the Cu(II) salt [84], and the cyclization of the π

• /carboxylation reaction. Plausible catalytic cycle for the cyclization/carboxylation of alkenylindoles, adapted from Liu et al. [81]. Intramolecular domino reactions of indolylallylamides through alkenylation/halogenation or alkenylation/esterification processes. Proposed mechanism for the alkenylation

trans-2-(2,5-Dimethoxy-4-iodophenyl)cyclopropylamine and trans-2-(2,5-dimethoxy-4-bromophenyl)cyclopropylamine as potent agonists for the 5-HT₂ receptor family

• Adam Pigott,
• Stewart Frescas,
• John D. McCorvy,
• Xi-Ping Huang,
• Bryan L. Roth and
• David E. Nichols

Beilstein J. Org. Chem. 2012, 8, 1705–1709, doi:10.3762/bjoc.8.194

• arylcyclopropane carboxylic acids from the corresponding cinnamic acids, followed by halogenation. Conversion of arylcyclopropane carboxylic acids 10a,b to the amines 4 and 5, and chemical resolution of 4 into its enantiomers. Chemical resolution of arylcyclopropane carboxylic acid 9 followed by bromination

Highly selective synthesis of (E)-alkenyl-(pentafluorosulfanyl)benzenes through Horner–Wadsworth–Emmons reaction

• George Iakobson and
• Petr Beier

Beilstein J. Org. Chem. 2012, 8, 1185–1190, doi:10.3762/bjoc.8.131

• nitrogen [18] nucleophiles, and the oxidative nucleophilic substitution with Grignard and alkyllithium reagents [19]. Reduction of the nitro group in 1 or 2 to (pentafluorosulfanyl)anilines followed by acylation, SEAr halogenation or diazotization (with follow-up reactions) has also been described [11][20

Regioselective chlorination and bromination of unprotected anilines under mild conditions using copper halides in ionic liquids

• Han Wang,
• Kun Wen,
• Nurbiya Nurahmat,
• Yan Shao,
• He Zhang,
• Chao Wei,
• Ya Li,
• Yongjia Shen and
• Zhihua Sun

Beilstein J. Org. Chem. 2012, 8, 744–748, doi:10.3762/bjoc.8.84

• as supplementing oxygen or gaseous HCl. Keywords: halogenation; ionic liquids; oxydation; regioselectivity; solvent effects; Introduction Chlorination and bromination of aromatic rings are classical and widely performed transformations, which are useful in many multistep organic-synthesis

• or HCl gas. Thus, our new protocol offers a safer operational choice and reduced environmental impact when compared to direct chlorination in aqueous HCl, or halogenation of protected/masked anilines, which requires additional deprotection processes. Chlorination (or bromination) of unprotected

Aryl nitrile oxide cycloaddition reactions in the presence of pinacol boronic acid ester

• Sarah L. Harding,
• Sebastian M. Marcuccio and
• G. Paul Savage

Beilstein J. Org. Chem. 2012, 8, 606–612, doi:10.3762/bjoc.8.67

• halogenation–dehydrohalogenation process is most common, several methods involving direct oxidative dehydrogenation of aldoximes have been reported, including the use of lead tetraacetate [22][23], mercury(II) acetate [24], hypervalent iodine [25][26], and manganese(IV) oxide [27]. We were interested in

Derivatives of phenyl tribromomethyl sulfone as novel compounds with potential pesticidal activity

• Krzysztof M. Borys,
• Maciej D. Korzyński and
• Zbigniew Ochal

Beilstein J. Org. Chem. 2012, 8, 259–265, doi:10.3762/bjoc.8.27

• compound is the key intermediate for all further transformations, we decided to check whether the use of bromine-substituted aromatic methylsulfone 4' would prove to offer higher yields in the halogenation/nitration sequence. Bromination of 4' with BrCl afforded tribromomethyl sulfone 1' in 90% yield

• of the obtained compounds exhibit fungicidal activity. Retrosynthetic analysis of the designed target molecules. Synthetic routes for 4-chlorophenyl tribromomethyl sulfone (1). Halogenation/nitration sequence for 4-halogenphenyl methyl sulfones 4 and 4'. SNAr transformations of sulfone 6. Preparation