Halogen-containing thiazole orange analogues – new fluorogenic DNA stains

• Aleksey A. Vasilev,
• Meglena I. Kandinska,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• David Sucunza,
• Juan J. Vaquero,
• Obis D. Castaño,
• Stanislav Baluschev and
• Silvia E. Angelova

Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283

• also noteworthy that the presence of the Br substituent in the C-5 position of the benzothiazole system does not influence the positions of the absorption maxima (cf. 5a vs 5c and 5b vs 5d) but does lead to a decrease in the molar absorptivity (up to 20% from 5b to 5d). The addition of dsDNA to the dye

• for deactivation of the excited state [43]. The replacement of the hydrogen atom at the C-5 position in the benzothiazole side of the molecules with a bromo substituent does not have any significant influence on the fluorescence of dyes 5c and 5d, which is similar to its effect on the absorption

• spectra and is in contrast to the by Armitage et al. observed influence of the replacement of hydrogen with fluorine atom in the benzothiazole ring [43]. Photostability The photostability of all dyes in the series was evaluated in acetonitrile with irradiation at 254 nm with a mercury lamp in equal

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

• •CCl3 radicals are quenched to CHCl3 via HAT [93]. The proposed catalytic cycle for the synthesis of benzo[4,5]thiazolo[3,2-a]pyrimidin-4-ones is as follows. The Lewis acidic InIII metal center coordinates to the more nucleophilic benzothiazole N atom, forming an adduct A [98]. This activates the N–H

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• ]. Jang and co-workers reported a mechanochemical synthesis of benzimidazoles [143][144], benzoxazole [145] and benzothiazole derivatives in presence of ZnO nano particles as catalyst [146]. Using 0.5 mol % of ZnO nano particles which were grown on aromatic imine D as capping agent, resulted in the best

• synthesis under mechanochemical conditions. Phosphonylation of benzothiazole and thiazole derivatives were done with organophosphorus compounds using 3 equiv of Mn(OAc)3·2H2O in a mixer mill for 1.5 h. Benzothiazole or thiazole rings having electron-donating or -withdrawing groups worked efficiently under

• [120]. Mechanochemical Hantzsch pyrrole synthesis [121]. Mechanochemical Biginelli reaction by subcomponent synthesis approach [133]. Mechanochemical asymmetric multicomponent reaction[134]. Mechanochemical Paal–Knorr pyrrole synthesis [142]. Mechanochemical synthesis of benzothiazole using ZnO nano

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

• , benzothiazole and N-methylimidazole was studied in the presence of three alternative catalytic systems: Pd(dba)2/DavePhos/Cs2CO3, Pd(PPh3)4/PivOH/K2CO3 and Pd(OAc)2/Cu(OAc)2/PPh3/K2CO3. The first catalytic system was found to be successful in the reaction with benzoxazole, the second one was less efficient for

• 24.4), benzothiazole (pKa 27.3), and N-methylbenzimidazole (pKa 32.5) [30]. Starting mono- and di(p-bromophenyl)-substituted porphyrins 1 and 11 were synthesized according to a described procedure [31], their analogues 2, 10, 12 were obtained using essentially the same approach. Results and Discussion

• Zinc meso-(4-bromophenyl)porphyrinate (1) was chosen as a model substrate for the investigation of the conditions of the catalytic arylation. The reaction with benzothiazole was first catalyzed with Pd(OAc)2/DavePhos (2-dicyclohexylphosphino-2’-dimethylaminobiphenyl) (20:20 mol %) and carried out in

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• promising component of PDT [22][23]. Whether squaraines follow the type I or type II mechanism is discussed controversially in the literature. Santos et al. [19][20], Salice et al. [24] and Rapozzi et al. [25] investigated how benzothiazole-squaraines, which are also pursued in this project, cause

• irradiation of benzothiazole-squaraines results in a photodegradation process. Rapozzi et al. assume that oxidation probably involves through formation of a π-complex between the electron-rich enamine double bond and molecular oxygen. In comparison to the photo-oxidation of enaminon or other electron-rich

• enhance the potential of the nanocarrier. Results and Discussion Adamantane-substituted squaraine (AdSq) was synthesized in a three step synthesis. Benzothiazole rings were introduced to enlarge the π-system. The sulfur atoms of these moieties increase the intersystem crossing due to the heavy atom effect

Selective and eco-friendly procedures for the synthesis of benzimidazole derivatives. The role of the Er(OTf)₃ catalyst in the reaction selectivity

• Natividad Herrera Cano,
• Jorge G. Uranga,
• Mónica Nardi,
• Antonio Procopio,
• Daniel A. Wunderlin and
• Ana N. Santiago

Beilstein J. Org. Chem. 2016, 12, 2410–2419, doi:10.3762/bjoc.12.235

• ][7] or benzothiazole [8][9] rings in numerous compounds is an important structural element for their biological and medical applications. For example benzimidazoles are widely spread in antiulcer, antihypertensive, antiviral, antifungal, anticancer, and antihistaminic medicines, among others [10][11

Economical and scalable synthesis of 6-amino-2-cyanobenzothiazole

• Jacob R. Hauser,
• Hester A. Beard,
• Mary E. Bayana,
• Katherine E. Jolley,
• Stuart L. Warriner and
• Robin S. Bon

Beilstein J. Org. Chem. 2016, 12, 2019–2025, doi:10.3762/bjoc.12.189

• ) connected to a 20 mL disposable syringe with an 8 inch, 16 gauge Luer fitting syringe needle. Reaction procedures 2-Chloro-6-nitro-1,3-benzothiazole (6) [15][20] 2-Chloro-1,3-benzothiazole (16, 10.0 g, 58.95 mmol) was added portion wise to concentrated H2SO4 (60 mL) in a cooled round-bottomed flask (ice

• –194 °C (EtOH); 1H NMR (500 MHz, CDCl3) δ 8.75 (d, J = 2.3 Hz, 1H, CH-7), 8.38 (dd, J = 9.0, 2.3 Hz, 1H, CH-5), 8.07 (d, J = 9.0 Hz, 1H, CH-4); 13C NMR (125 MHz, CDCl3) δ 158.9 (C-2), 154.9 (C-6), 145.6 (C-7a), 136.6 (C-3a), 123.5 (CH-4), 122.4 (CH-5), 117.8 (CH-7). 6-Nitro-1,3-benzothiazole-2

• -carbonitrile (13) [19] A solution of NaCN (2.40 g, 48.97 mmol) in H2O (100 mL) was added slowly to a stirred solution of 2-chloro-6-nitro-1,3-benzothiazole (6, 10.0 g, 46.59 mmol) and DABCO (748 mg, 6.99 mmol) in MeCN (1000 mL). The reaction mixture was stirred at room temperature for 24 h. Excess cyanide was

Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu²⁺

• Rahman Hosseinzadeh,
• Mohammad Nemati,
• Reza Zadmard and
• Maryam Mohadjerani

Beilstein J. Org. Chem. 2016, 12, 1749–1757, doi:10.3762/bjoc.12.163

• ]arene bearing anthraceneisoxazolymethyl [3], quinolone [28], 5-nitrosalicylaldehyde [29], 3-alkoxy-2-naphthoic acid [30], coumarine [31] and benzothiazole [10][15] groups. In continuation of our studies on developing novel chemosensors containing fluorenyl moieties as fluorogenic group [32][33][34], we

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• 1,2-dihydropyridine-3-phosphonate 259. Yavari et al. have described the phosphorylation of benzothiazole (263) and isoquinoline (246) through a one-pot three-component reaction with activated acetylenes 260 and diphenyl phosphonate (261) under solvent-free conditions at room temperature (Scheme 54

• -phosphonates and 2-acyl-1,2-dihydroisoquinoline-1-phosphonates. Three-component reaction of pyridine derivatives with ethyl propiolate and dialkyl phosphonates. Three-component reactions for the phosphorylation of benzothiazole and isoquinoline. Three-component synthesis of diphenyl [2-(aminocarbonyl)- or [2

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• significantly higher than those displayed by the parent 2-(2-hydroxyphenyl)benzoxazole (0.02) and 2-(2-hydroxyphenyl)benzothiazole (0.005) [34]. Conclusion The ring expansion of the 3,4,5,6-tetrachloro-1,2-benzoquinones occuring under coupling with 2-methylbenzoxazoles, 2-methylbenzothiazoles and 2,3,3

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

• ). The catalytic iodination of electron deficient 1,3-azoles was recently realized by Zhao et al. Under the catalytic conditions consisting of LiOt-Bu, 1,10-phenanthroline and CuBr2, a class of different conventional azoles 17, including benzoxazoles, benzothiazole, N-methylbenzimidazole, 5-phenyloxazole

Highly selective palladium–benzothiazole carbene-catalyzed allylation of active methylene compounds under neutral conditions

• Antonio Monopoli,
• Pietro Cotugno,
• Carlo G. Zambonin,
• Francesco Ciminale and
• Angelo Nacci

Beilstein J. Org. Chem. 2015, 11, 994–999, doi:10.3762/bjoc.11.111

• from Pd2dba3 and 3-methylbenzothiazolium salt V as precursors. A comparison of the performance of benzothiazole carbene with phosphanes and an analogous imidazolium carbene ligand is also proposed. Keywords: active methylene compounds; allylic carbonates; Pd–benzothiazol-2-ylidene complex; Tsuji–Trost

• , catalyst loading, temperature and solvents (Table 1). With regard to the influence of ligands, the efficiency of benzothiazole–carbene was compared with that of sulfides II and III, both in the presence and in the absence of PPh3, as it is well known that also chelating N-heterocyclic ligands bearing

• Herrmann et al. [40], prepared in situ from 1,3-dimethylimidazolium iodide (VI). The reaction carried out under the protocol conditions afforded in 2 h the monoallylated compound 1 in a low yield (16%) confirming the superior efficiency of benzothiazole–carbene (Table 1, entry 16). A possible explanation

A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

• Stefanie Wolfram,
• Hendryk Würfel,
• Stefanie H. Habenicht,
• Christine Lembke,
• Phillipp Richter,
• Eckhard Birckner,
• Rainer Beckert and
• Georg Pohnert

Beilstein J. Org. Chem. 2014, 10, 2470–2479, doi:10.3762/bjoc.10.258

• also used for probing in life science comprises the heterocyclic thiazoles. This structural element can be found in commercial products, such as thiazole orange, SYBR® Green I or TOTO®, which are, e.g., used for DNA labeling. In these compounds the thiazole ring is part of a benzothiazole. We set out

One-pot three-component synthesis and photophysical characteristics of novel triene merocyanines

• Christian Muschelknautz,
• Robin Visse,
• Jan Nordmann and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 599–612, doi:10.3762/bjoc.10.51

• of the most stable isomers of these novel triene merocyanines was assigned to be 2E,4Z,6Z for both the Fischer’s base derivatives 10a–g (X = CMe2) and the benzothiazole derivative 10h (X = S) (Figure 3). Since the stereoconvergent-product formation (only single sets of signals are obtained in the NMR

Four-component reaction of cyclic amines, 2-aminobenzothiazole, aromatic aldehydes and acetylenedicarboxylate

• Hong Gao,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 2934–2939, doi:10.3762/bjoc.9.330

• : benzothiazole; domino reaction; electron-deficient alkyne; multicomponent reaction; pyrrolidinone; Introduction Over fifty years ago, Huisgen firstly described the addition reactions of nitrogen-containing heterocycles to electron-deficient alkynes to form 1,4-dipolar intermediates, which can reacted

• preparation of the mixed heterocyclic compounds containing units of benzothiazole, piperidine and 2-pyrrolidinone in satisfactory yields. The range of substrates and the reaction mechanism for this reaction were briefly discussed. This convenient synthetic reaction might be potentially used for complex

Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• is present in the ligand, the others can be replaced by benzothiazole rings. The rate of reaction in the CuAAC test reaction increases in the order (Bth)3 << (Bth)(BimH)2 < (BimH)3 << (Bth)2(BimH) [80][83]. With carboxylic acid or ester groups attached to the benzimidazole rings via alkyl chains (CH2

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

• Todd J. Eckroat,
• Abdelrahman S. Mayhoub and
• Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

• (9) and diphenyl-1,3,4-oxadiazole (10); and thioflavin-T analogues such as benzothiazole (11), benzoxazole (12), benzofuran (13), imidazopyridine (14), and benzimidazole (15); as well as quinoline (16) and naphthalene (17) derivatives (Figure 1B). In this review, we provide an overview of these AD

• : BTA = 2-(4'-methylaminophenyl)benzothiazole, Figure 2), was prepared by methylation of 4-(6-methyl-2-benzothiazolyl)aniline using [11C]methyl iodide [49]. Compared to 4, 56a showed greatly increased lipophilicity and improved binding affinity for Aβ1-40 (Ki = 890 nM for 4 and Ki = 20.2 for 56a). In

• amide 69, which was subsequently converted to the thioamide by using Lawesson’s reagent and cyclized to form the benzothiazole core 70 (Scheme 6B). Demethylation with BBr3 and protection of the resulting hydroxy moiety as the methoxymethyl (MOM) ether gave 71. Reduction of the nitro group to 72

Isotopically labeled sulfur compounds and synthetic selenium and tellurium analogues to study sulfur metabolism in marine bacteria

• Nelson L. Brock,
• Christian A. Citron,
• Claudia Zell,
• Martine Berger,
• Irene Wagner-Döbler,
• Jörn Petersen,
• Thorsten Brinkhoff,
• Meinhard Simon and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 942–950, doi:10.3762/bjoc.9.108

• order rhizobiales, a close relative of Roseobacter clade bacteria. In addition, the sulfur volatiles bis(methylthio)methane (22), S-methyl propanethioate (23), 4-(methylthio)butan-2-one (24), S-methyl 3-(methylthio)propanethioate (25), and benzothiazole (26) were found in strain-specific patterns

Synthesis of 2,3-dihydronaphtho[2,3-d][1,3]thiazole-4,9-diones and 2,3-dihydroanthra[2,3-d][1,3]thiazole-4,11-diones and novel ring contraction and fusion reaction of 3H-spiro[1,3-thiazole-2,1'-cyclohexanes] into 2,3,4,5-tetrahydro-1H-carbazole-6,11-diones

• Lidia S. Konstantinova,
• Kirill A. Lysov,
• Ljudmila I. Souvorova and
• Oleg A. Rakitin

Beilstein J. Org. Chem. 2013, 9, 577–584, doi:10.3762/bjoc.9.62

• , there exists only a single example of the thiazole conversion to thiazole-2-thione, i.e., heating of 3-methyl-2,3-dihydro-1,3-benzothiazole with elemental sulfur at 200 °C for 0.5 h giving 3-methyl-1,3-benzothiazole-2(3H)-thione [17]. We described a similar conversion of the methylene group to

Efficient Cu-catalyzed base-free C–S coupling under conventional and microwave heating. A simple access to S-heterocycles and sulfides

• Silvia M. Soria-Castro and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2013, 9, 467–475, doi:10.3762/bjoc.9.50

• h at 110 °C, has also been reported [52]. As part of our ongoing study on sulfur chemistry, we are interested in the one-pot synthesis of target heterocycles such as the Beaucage reagent and benzothiazole as well as sulfides by using Cu-catalysis to mediate the C–S bond formation. Herein, we report

• explored the possibility of building a benzothiazole ring by copper-catalyzed reaction of N-(2-iodophenyl)acetamide (13) with 1. Thus, together with benzothiazole 14, the reaction of 13 and 1 in a 1:1.5 ratio, in the presence of CuI/1,10-phenanthroline after 24 h of conventional heating, afforded low

A quantitative approach to nucleophilic organocatalysis

• Herbert Mayr,
• Sami Lakhdar,
• Biplab Maji and
• Armin R. Ofial

Beilstein J. Org. Chem. 2012, 8, 1458–1478, doi:10.3762/bjoc.8.166

• atom in the benzothiazole by a NCH3 group (55b → 55c) shows that imidazole derivatives are approximately four orders of magnitude more reactive than structurally analogous thiazole derivatives, which can, again, be assigned to the different electronegativities of sulfur and nitrogen. Conclusion

Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

• Cécile Verrier,
• Pierrik Lassalas,
• Laure Théveau,
• Guy Quéguiner,
• François Trécourt,
• Francis Marsais and
• Christophe Hoarau

Beilstein J. Org. Chem. 2011, 7, 1584–1601, doi:10.3762/bjoc.7.187

• -formylthiophene by using Cu(I) cocatalyst and 1,10-phenanthroline in DMA solvent (Scheme 31a) [82]. This year, Oliaf studied more specifically the palladium- and copper-catalyzed oxidative C–H/C–H cross-coupling of various electron-rich 1,3-diazoles and reported notably the direct coupling of benzothiazole with

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• reagent (3,3-dimethyl-2,3-dihydro-1,2-benzothiazole-1,1-dioxide) [86][87]; p-TsN(F)Me [88]; NFColl = N-fluorocollidinium tetrafluoroborate and NFPy = N-fluoropyridinium tetrafluoroborate [72][89]; F2-bipy = 1,1'-difluoro-bipyridinium bis(tetrafluoroborate) [90]. 1H NMR spectra of a species of the type A

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• intermediacy of the acyclic cyano derivative 127 (Scheme 34) [76]. Hydrazonoyl chlorides 129 on treatment with benzothiazole-2-acetonitrile in ethanolic sodium ethoxide solution at room temperature afforded intermediate hydrazones 130 which on cyclization gave products identified as 3-substituted 5-amino-1