Oxidative radical ring-opening/cyclization of cyclopropane derivatives

• Yu Liu,
• Qiao-Lin Wang,
• Zan Chen,
• Cong-Shan Zhou,
• Bi-Quan Xiong,
• Pan-Liang Zhang,
• Chang-An Yang and
• Quan Zhou

Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23

• radical intermediate 76. The intermediate 77, produced by the intramolecular cyclization of intermediate 76, reactes with diphenyl diselenide 73 to form the target product 74 via homolytic substitution (SH). In 2013, Ryu and co-workers developed the bromine radical-mediated ring-opening and alkylation of

• diaryl diselenides. Bromine radical-mediated ring-opening of alkylidenecyclopropanes. Fluoroalkyl (Rf) radical-mediated ring-opening of MCPs. Visible-light-induced alkylation/ring-opening/cyclization of cyclopropyl olefins with bromides. Mn(III)-mediated ring-opening and [3 + 3]-annulation of

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• . Intermediary diacid was first esterified with diazomethane, then the isopropylidene acetal was hydrolyzed, and diester saponification gave N-Boc-protected compound (2S,3R)-35. Via ketopinic acid functionalized 2(3H)-oxazolones When oxazolone 36 derived from (R)-(−)-ketopinic acid was reacted with bromine and

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• halogenohydroxylation (Hal = I, Br) or addition–elemination of bromine (forming bromobutadienes) with high stereoselectivity [25][26]. Apart from that, reactions of sulfur containing allenes were studied in acidic media [27][28]. Despite promising results, there was no further research in this area. Based on our recent

Pd-Catalyzed microwave-assisted synthesis of phosphonated 13α-estrones as potential OATP2B1, 17β-HSD1 and/or STS inhibitors

• Rebeka Jójárt,
• Szabolcs Pécsy,
• György Keglevich,
• Mihály Szécsi,
• Réka Rigó,
• Csilla Özvegy-Laczka,
• Gábor Kecskeméti and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 2838–2845, doi:10.3762/bjoc.14.262

• temperature greatly depends on the nature of the C-3 substituent and on the position of the bromine, not on the size and polarity of the P-coupling agent. In the case of 3-benzyl ethers 3 and 6, solvent change from acetonitrile to toluene was required. This might be attributed to the decreased polarity of the

Targeting the Pseudomonas quinolone signal quorum sensing system for the discovery of novel anti-infective pathoblockers

• Christian Schütz and
• Martin Empting

Beilstein J. Org. Chem. 2018, 14, 2627–2645, doi:10.3762/bjoc.14.241

• besides PqsR [68]. Experiments with a PqsR isogenic mutant strain revealed that 52 inhibits HHQ and PQS production, while raising 2-AA levels, pointing at PqsBC as a second target, which was corroborated via SPR studies. When exchanging the chlorine to bromine 53 a high PqsR activity was obtained while

Some mechanistic aspects regarding the Suzuki–Miyaura reaction between selected ortho-substituted phenylboronic acids and 3,4,5-tribromo-2,6-dimethylpyridine

• Piotr Pomarański,
• Piotr Roszkowski,
• Jan K. Maurin,
• Armand Budzianowski and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2018, 14, 2384–2393, doi:10.3762/bjoc.14.214

• due to electronic reasons, but is strongly disfavoured by steric repulsion (bigger van der Waals radius of the bromine atom compared to the methyl group). This may be the reason for the first arylation to occur at the C-3(5) position in compound 4 and the second one preferably at the C-4 position

D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation

• Michael R. Imrich,
• Jochen Kraft,
• Cäcilia Maichle-Mössmer and
• Thomas Ziegler

Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182

• ligands 2 and 3 and spiro-fused PyOx and PHOX ligands 4 and 5. Molecular structure of 10j. Ellipsoids are given at the 50% probability level. Grey = carbon, red = oxygen, white = hydrogen, purple = nitrogen, orange = bromine. Preparation of 1,2-isopropylidene-protected D-fructose derivatives with

Host–guest complexes of conformationally flexible C-hexyl-2-bromoresorcinarene and aromatic N-oxides: solid-state, solution and computational studies

• Rakesh Puttreddy,
• Ngong Kodiah Beyeh,
• S. Maryamdokht Taimoory,
• Daniel Meister,
• John F. Trant and
• Kari Rissanen

Beilstein J. Org. Chem. 2018, 14, 1723–1733, doi:10.3762/bjoc.14.146

• of 8 and those of BrC6 in 8@BrC6 are parallel to each other. As a result, the bromine of the C–Br bond and the C2-position establish short contacts of 3.52 Å. However, the prominent interactions responsible for locking the H–G complex are the C–H···π (ca. 2.92 Å) and C–H···O (ca. 2.61 and 2.71 Å

• shifts’ changes are substantially increased when more electron-donating groups are present on the aromatic N-oxides such as with 5 (two methyl groups) and 9 (two methoxy groups, Figures S5 and S9, Supporting Information File 1). This is expected as the four electron-withdrawing bromine groups on the BrC6

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• by column chromatography. Other efforts (not detailed in the present report), such as manipulation under dark conditions or replacing the iodine in the alkylating reagent by bromine, provided even more unsatisfactory results, e.g., the O-mono-alkylated product. By contrast, the double amination of

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• the CuSAC reaction. First, it apparently fails with 3-alkyl sydnones and also with almost all 4-substituted 3-phenylsydnones except 4-F [44], 4-Cl and 4-Br derivatives [119]. However, this fortunate exception gave the further possibility to exchange halogen (especially bromine) by either an aryl

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• (Scheme 8). After bromination of 40 with molecular bromine in carbon tetrachloride, direct dehydrobromination with lithium chloride in dimethylformamide gave 11 in 85% isolated yield. Müller’s group reported an alternative synthesis for 11 starting from the carbene adduct 41 over two or three steps [55

• bromination of Julia’s ketone 163 followed by spontaneous elimination of hydrogen bromide at the temperature of the reaction. 2,3-Benzotropone (12) was also prepared by bromination of 1-benzosuberone (162) using both NBS and molecular bromine followed by dehydrobromination (using lithium chloride in

• selenium dioxide in boiling ethanol, followed by dehydrogenation with bromine in acetic acid at 100 °C. Another method for the synthesis of 7-hydroxy-2,3-benzotropone (241) starting from the reaction of diketone 276 with boiling acetic anhydride was achieved by Maignan (Scheme 44) [168]. The reaction of

Iodine(III)-mediated halogenations of acyclic monoterpenoids

• Laure Peilleron,
• Tatyana D. Grayfer,
• Joëlle Dubois,
• Robert H. Dodd and
• Kevin Cariou

Beilstein J. Org. Chem. 2018, 14, 1103–1111, doi:10.3762/bjoc.14.96

• . If the reductive elimination only occurred after a second ligand exchange it would then give X2 which is generally a less efficient electrophilic species than the corresponding acetoxyhypohalite, especially trifluoroacetoxyhypohalites [26]. Indeed, when we reacted geranyl acetate 1a with bromine we

Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

• Toshifumi Dohi,
• Shohei Ueda,
• Kosuke Iwasaki,
• Yusuke Tsunoda,
• Koji Morimoto and
• Yasuyuki Kita

Beilstein J. Org. Chem. 2018, 14, 1087–1094, doi:10.3762/bjoc.14.94

• initiated by the decomposition of PIFA to form the trifluoroacetoxy radical under visible light irradiation [50]. Our approach for the generation of radical species for the benzylic carboxylation using a hypervalent iodine reagent relies on the unique reactivity of the hypervalent iodine(III)–bromine bond

• the potassium salt, were unsuccessful in forming the carboxylate 2a (Table 1, entries 2–4). The reason for this behavior was thought to be because lithium bromide or organic bromides in combination with PIDA generated the electrophilic ‘Br+’ species [71] and molecular bromine [72], or hypobromite and

Electrochemically modified Corey–Fuchs reaction for the synthesis of arylalkynes. The case of 2-(2,2-dibromovinyl)naphthalene

• Fabiana Pandolfi,
• Isabella Chiarotto and
• Marta Feroci

Beilstein J. Org. Chem. 2018, 14, 891–899, doi:10.3762/bjoc.14.76

• alkyne (Et4NBF4) or the bromoalkyne (NaClO4). This study allowed to establish that 2-(bromoethynyl)naphthalene can be converted into 2-ethynylnaphthalene by cathodic reduction. Keywords: arylalkyne; carbon–bromine bond cleavage; cathodic reduction; Corey–Fuchs reaction; 2-(2,2-dibromovinyl)naphthalene

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

• so that it was prone to produce 4a, as depicted in path b, particularly in the absence of the coupling counterpart 2. Besides, alkaline and high energy input conditions promoted the dehalogenation as shown in path c, while the addition of bromine salts helped diminishing this effect dramatically [56

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• identifying the caesium–bromine pair was optimal for the conversion, caesium carbonate was the base of choice for the described stepwise study with ethanol. Tuning liquid-assisted grinding with ethanol Because using ethanol (high dielectric constant) as the LAG solvent afforded the highest conversion to

Synthesis and stability of strongly acidic benzamide derivatives

• Frederik Diness,
• Niels J. Bjerrum and
• Mikael Begtrup

Beilstein J. Org. Chem. 2018, 14, 523–530, doi:10.3762/bjoc.14.38

• (9c) was found to be much more stable under these conditions, which is promising for future applications in proton conducting materials. Conclusion In summary, it has been demonstrated that novel mono- or bis-trifluoromethanesulfonamide derivatives of benzoic acids bearing a reactive group (bromine or

One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na₂S₂O₈

• Teppei Sasaki,
• Katsuhiko Moriyama and
• Hideo Togo

Beilstein J. Org. Chem. 2018, 14, 345–353, doi:10.3762/bjoc.14.22

• [27], with R-CH=O/(n-Bu)4NBr (TBAB, cat.)/K2S2O8 at 90 °C [28], with ArSO2H/Eosin Y(cat.)/tert-butyl hydrogen peroxide (TBHP) at rt [29], and with ArSO2NHNH2/n-Bu4NI(cat.)/TBHP at 80 °C [30]. In addition, the formation of coumarins via the bromine-radical-mediated reaction of aryl 2-alkynoates with

Conformational preferences of α-fluoroketones may influence their reactivity

• Graham Pattison

Beilstein J. Org. Chem. 2017, 13, 2915–2921, doi:10.3762/bjoc.13.284

• lone pairs and the filled C=O π-orbital. The higher polarizability of higher halogens such as chlorine and bromine may be able to reduce this repulsion, however, the tightly held, non-polarizable lone pairs of fluorine are likely to experience this repulsive effect most strongly. The shorter C–F bond

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• using sodium bromate, NaBrO3, as a bromine source (Scheme 22) [43]. The photoredox-catalysed chloro-, bromo- and also (trifluoromethylthio)trifluoromethylation of unactivated alkenes was studied by Liu and co-workers in 2017 (Scheme 23) [44]. The Langlois reagent was combined with N-halophthalimides 42a

Syntheses, structures, and stabilities of aliphatic and aromatic fluorous iodine(I) and iodine(III) compounds: the role of iodine Lewis basicity

• Tathagata Mukherjee,
• Soumik Biswas,
• Andreas Ehnbom,
• Subrata K. Ghosh,
• Ibrahim El-Zoghbi,
• Nattamai Bhuvanesh,
• Hassan S. Bazzi and
• John A. Gladysz

Beilstein J. Org. Chem. 2017, 13, 2486–2501, doi:10.3762/bjoc.13.246

• . 1.5% lower (4851.7(4) vs 4920.1(3) Å3), apropos to the smaller bromine atom. The space group is both chiral and polar, and the unit cell dimensions of both compounds feature c values (5.5976(2)–5.5624 Å) that are much smaller than the a and b values (29.6474(9)–29.5335(13) Å). As noted earlier and

Solvent-free copper-catalyzed click chemistry for the synthesis of N-heterocyclic hybrids based on quinoline and 1,2,3-triazole

• Martina Tireli,
• Silvija Maračić,
• Stipe Lukin,
• Marina Juribašić Kulcsár,
• Dijana Žilić,
• Mario Cetina,
• Ivan Halasz,
• Silvana Raić-Malić and
• Krunoslav Užarević

Beilstein J. Org. Chem. 2017, 13, 2352–2363, doi:10.3762/bjoc.13.232

• Information File 1, Figure S22). Thus, the molecular structures differ in the substituent bonded to the C24 atom of the C21–C26 phenyl ring, which is chlorine in 5, bromine in 6, iodine in 7, and hydrogen in 8. The corresponding bond lengths in these structures are similar, as well as the conformations of the

Diosgenyl 2-amino-2-deoxy-β-D-galactopyranoside: synthesis, derivatives and antimicrobial activity

• Henryk Myszka,
• Patrycja Sokołowska,
• Agnieszka Cieślińska,
• Andrzej Nowacki,
• Maciej Jaśkiewicz,
• Wojciech Kamysz and
• Beata Liberek

Beilstein J. Org. Chem. 2017, 13, 2310–2315, doi:10.3762/bjoc.13.227

• in the glycosylation. This mixture of 2 is chromatographically inseparable due to the highly reactive nature of the bromine group at the anomeric carbon, but, the anomers of 2 are readily distinguishable in the NMR spectrum (δ 6.65, d, J1,2 = 3.7 Hz for the α anomer and δ 6.35, d, J1,2 = 9.6 Hz for

Phosphonic acid: preparation and applications

• Charlotte M. Sevrain,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2017, 13, 2186–2213, doi:10.3762/bjoc.13.219

• of DMSO [26] and a catalytic amount of iodide as exemplified by the synthesis of compound 127 by oxidation of 126 [240] (Figure 36A). This method was also applied to prepare 1-aryl-1-hydroxymethylphosphonic acid [241]. HgCl2 [242] or bromine water are also efficient for the oxidation of phosphinic

• acid. As an example, the phosphinic acid 128 (Figure 36B) which is prepared by the addition of hypophosphorous acid on imine, was converted quantitatively in α-amino phosphonic acid 129 with bromine water [243] (Figure 36B). HgCl2, despite its toxicity and environmental hazard is nevertheless an

Preactivation-based chemoselective glycosylations: A powerful strategy for oligosaccharide assembly

• Weizhun Yang,
• Bo Yang,
• Sherif Ramadan and
• Xuefei Huang

Beilstein J. Org. Chem. 2017, 13, 2094–2114, doi:10.3762/bjoc.13.207

• developed a preactivation-based glycosylation approach using selenoglycosides via the intermediacy of β-glycosyl bromides (Scheme 3) [27][28]. Upon the addition of 0.5 equiv of bromine, half of the selenoglycoside donor 4 would be activated to presumably form glycosyl bromide 5 accompanied by the generation

• disaccharide 7, which could be subjected to bromine-promoted glycosylation for further chain elongation. As an example, preactivation of a monosaccharide 8 with bromine was followed by the addition of a bifunctional disaccharide building block 10 and subsequent TMSOTf-promoted orthoester rearrangement