Novel solid-phase strategy for the synthesis of ligand-targeted fluorescent-labelled chelating peptide conjugates as a theranostic tool for cancer

• Sagnik Sengupta,
• Mena Asha Krishnan,
• Premansh Dudhe,
• Ramesh B. Reddy,
• Bishnubasu Giri,
• Sudeshna Chattopadhyay and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2018, 14, 2665–2679, doi:10.3762/bjoc.14.244

• , 28.0; HRMS (ESI) m/z: [M + Na]+ calcd for C30H46N2O9, 601.3096; found, 601.3092. Procedure for debenzylation of benzyl tris(tert-butoxy)-protected DUPA precursor 3 to give (S)-5-(tert-butoxy)-4-(3-((S)-1,5-di-tert-butoxy-1,5-dioxopentan-2-yl)ureido)-5-oxopentanoic acid (4): To a solution of benzyl tris

• = 5.0, 5.26, 7.76 Hz, 2H), 2.37–2.21 (m, 4H), 2.10–2.01 (m, 2H), 1.89–1.80 (m, 2H), 1.45 (s, 9H), 1.42 (s, 18H); 13C NMR (100 MHz, CDCl3) δ 176.1, 173.1, 172.5, 171.9, 157.8, 82.5, 82.1, 80.6, 53.3, 53.0, 31.5, 30.3, 28.4, 28.1, 28.0, 27.9, 27.8; HRMS (ESI) m/z: [M + Na]+ calcd for C23H40N2O9, 511.2626

• chromatography (RP-HPLC) tR = 9.8 min. The molecular mass is determined by LCMS. HRMS (+ESI) calcd for [M − Cl]+ (C89H121N14O21S)+: 1753.8546; found, 1753.8557. General procedure for solid-phase peptide synthesis of pteroate rhodamine B conjugate 17, pteroate-NH-(CH2)7CO-Lys(rhodamine B)-DAP-Asp-Cys: H-Cys(Trt

Design and synthesis of C₃-symmetric molecules bearing propellane moieties via cyclotrimerization and a ring-closing metathesis sequence

• Sambasivarao Kotha,
• Saidulu Todeti and
• Vikas R. Aswar

Beilstein J. Org. Chem. 2018, 14, 2537–2544, doi:10.3762/bjoc.14.230

• , 6H), 6.28 (s, 6H), 3.51–3.44 (m, 12H), 1.79 (d, J = 8.8 Hz, 3H), 1.61 (d, J = 8.8 Hz, 3H) ppm; 13C NMR (125 MHz, CDCl3) δ 177.0, 141.8, 141.3, 134.8, 131.4, 128.2, 127.2, 125.7, 52.4, 46.0, 45.7 ppm; HRMS (ESI, Q-ToF) m/z: [M + H]+ calcd for C51H40N3O6, 790.2912; found, 790.2918; IR (neat) max: 2918

• , 175.4, 136.7, 136.2, 136.1, 129.2, 126.5, 116.3, 49.1, 46.4, 35.4, 26.8 ppm; HRMS (ESI, Q-ToF) m/z: [M + Na]+ calcd for C19H19NO3·Na, 332.1257; found, 332.1254; IR (neat) max: 2325, 1671, 1263, 746 cm−1. Synthesis of trimerized compound 12 Based on the earlier procedure of trimerization, compound 13

• , 131.4, 128.1, 126.9, 125.6, 116.1, 49.1, 46.3, 35.5 ppm; HRMS (ESI, Q-ToF) m/z: [M + Na]+ calcd for C57H51N3O6·Na, 896.3670; found; 896.3678; IR (neat) max: 2342, 1709, 1512, 1183, 919, 736 cm−1. Synthesis of trimerized product 19 Based on the earlier procedure of trimerization, compound 18 (500 mg

Quinolines from the cyclocondensation of isatoic anhydride with ethyl acetoacetate: preparation of ethyl 4-hydroxy-2-methylquinoline-3-carboxylate and derivatives

• Nicholas G. Jentsch,
• Jared D. Hume,
• Emily B. Crull,
• Samer M. Beauti,
• Amy H. Pham,
• Julie A. Pigza,
• Jacques J. Kessl and
• Matthew G. Donahue

Beilstein J. Org. Chem. 2018, 14, 2529–2536, doi:10.3762/bjoc.14.229

• (DMSO-d6, 100 MHz) δ 158.8 (s, Ca), 146.7 (s, Cb), 140.6 (s, Cc), 139.3 (d, Cd), 130.5 (d, Ce), 117.6 (d, Cf), 114.5 (s, Cg), 112.4 (s, Ch); HRMS (ESI): calcd for [C8H4BrNO3 + Na]+ 263.926677; found: 263.926475; anal. calcd for C8H4BrNO3: C, 50.34; H, 3.90; found: C, 49.98; H, 3.80. General procedure

• ), 2.39 (s, 3H, Cl-H), 1.27 (t, J = 7.1 Hz, 1H, Cm-H); 13C NMR (DMSO-d6, 100 MHz) δ 172.0 (s, Ca), 166.4 (s, Cb), 149.4 (s, Cc), 138.0 (s, Cd), 134.9 (d, Ce), 127.1 (d, Cf), 126.0 (s, Cg), 120.6 (d, Ch), 116.3 (s, Ci), 115.0 (s, Cj), 60.4 (t, Ck), 18.2 (q, Cl), 14.1 (q, Cm); HRMS (ESI): calcd for

• Infectious Disease for AI127282. Funding for the Bruker UltraShield Plus 400 MHz NMR and ThermoFinnigan LXQ ESI LC–MS used in this research was provided by National Science Foundation Major Research Instrumentation under Grant Numbers 0840390 and 0639208, respectively. NGJ, JDH, and EBC thank the USM

Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• by ESI–TOF mass spectra, 1H and 13C NMR spectroscopy as well as 2D NMR spectra (Supporting Information File 1). The NMR data gave evidence of the structural assignment of the 5’-azido compounds and the macrocycles. A strong upfield shift (≈10 ppm) for the C5’-carbon signal as well as a moderate

• Information File 402: Experimental procedures, analytical data, NMR spectra, conformational analysis and crystallographic data. Acknowledgements We would like to thank Dr. M. Letzel, Universität Münster, Germany, for the ESI–TOF spectra and Prof. Dr. B. Wünsch, Institut für Pharmazeutische und Medizinische

The mechanochemical synthesis of quinazolin-4(3H)-ones by controlling the reactivity of IBX

• Md Toufique Alam,
• Saikat Maiti and
• Prasenjit Mal

Beilstein J. Org. Chem. 2018, 14, 2396–2403, doi:10.3762/bjoc.14.216

• ), multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, brs = broad singlet, m = multiplet), coupling constant (Hz) and integration. High-resolution mass spectra (HRMS) were recorded on an ESI–TOF (time of flight) mass spectrometer. IR (infrared) spectral data are reported in wave numbers (cm−1

A novel and practical asymmetric synthesis of eptazocine hydrobromide

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan,
• Kuaile Lin and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 2340–2347, doi:10.3762/bjoc.14.209

• Bruker 400 MHz spectrometer with TMS as an internal standard. Mass spectra were recorded with a Q-TOF mass spectrometer using electrospray positive ionization (ESI+). Enantiomeric ratios were determined by HPLC using a chiral column (Chiralpak AY-H) with hexane/isopropyl alcohol 50:50 as eluents

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

• Liudmila L. Rodina,
• Xenia V. Azarova,
• Jury J. Medvedev,
• Dmitrij V. Semenok and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200

• electrospray ionization (ESI-QTOF). Chemical shifts are reported in ppm, and coupling constants are given in hertz (Hz). All signals in NMR spectra were normalized relative to signals of CНCl3 (δ = 7.26 ppm in 1H NMR) and CDCl3 (δ = 77.0 in 13C NMR spectra). For single crystal X-ray diffraction experiments of

• ), 3.95–3.88 (m, 1H), 2.69–2.60 (m, 4H), 2.33–2.19 (m, 2H), 2.08–1.96 (m, 2H) ppm; 13C NMR (101 MHz, CDCl3, δ) 200.3, 198.7, 130.9, 92.5, 69.2, 33.3, 31.8, 31.2, 24.4 ppm; HRMS–ESI (m/z): [M + Na]+ calcd for C9H12N2O3, 219.0746; found, 219.0746. B. Sensitized photoexcitation of 2-diazo-3a,4,7,7a

• , 68.5, 52.0, 48.8, 45.9, 30.3, 24.4 ppm; HRMS–ESI (m/z): [M + Na]+ calcd for C14H16N2O3, 283.1059; found, 283.1065. C. Sensitized photoexcitation of 2-diazohexahydro-1H-4,7-methanoindene-1,3(2H)-dione (1c). The reaction was performed according to the general procedure with 376 mg (2 mmol, 1 equiv) of

Investigation of the electrophilic reactivity of the biologically active marine sesquiterpenoid onchidal and model compounds

• Melissa M. Cadelis and
• Brent R. Copp

Beilstein J. Org. Chem. 2018, 14, 2229–2235, doi:10.3762/bjoc.14.197

• determined by 1H NMR. Purification of the crude reaction product gave 29 as the free base (15% yield) and as the salt, 30 (also 15% yield, Figure 3). Spectroscopic and spectrometric analysis of 29 confirmed the formation of a diamine adduct, with detection of a protonated molecular ion in the (+)-ESI mass

• deconvoluted (+)-ESI mass spectrum, identifying a total lysozyme modification yield of 15% (Table 1). The presence of a large amount of unmodified lysozyme (85%), even after 72 h, was attributed to the slow reactivity of the enol acetate functionality of onchidal, as observed in the original model studies

Calix[6]arene-based atropoisomeric pseudo[2]rotaxanes

• Carmine Gaeta,
• Carmen Talotta and
• Placido Neri

Beilstein J. Org. Chem. 2018, 14, 2112–2124, doi:10.3762/bjoc.14.186

• stoppering or catenation of such atropoisomeric pseudorotaxanes. Experimental ESI(+)–MS measurements were performed on a Micromass Bio-Q triple quadrupole mass spectrometer equipped with electrospray ion source, using a mixture of H2O/CH3CN (1:1) and 5% HCOOH as solvent. Flash chromatography was performed on

• (respect chloride salt); mp 135–138 °C; ESI(+) MS (m/z): 350.2 (M+); 1H NMR (400 MHz, CD3OD, 298 K) δ 4.34 (s, 4H), 7.37–7.41 (overlapped, 6H), 7.61–7.67 (overlapped, 20H), 7.76 (d, J = 7.8 Hz, 4H); 13C NMR (100 MHz, CD3OD, 298 K) δ 51.7, 118.4, 118.4, 118.5, 121.7, 124.4, 127.1, 128.0, 128.8, 129.0, 130.0

• , 130.1, 130.2, 130.3(2), 130.5(2), 130.6, 131.2, 131.5, 135.8, 141.3, 143.9, 162.1, 162.6, 163.1, 163.6; anal. calcd for C58H36BF24N: C, 57.40; H, 2.99; found: C, 57.39; H, 3.01. Derivative 3+ Light brown solid, 0.57 g, 0.48 mmol, 70 % yield (respect chloride salt); mp 125–128 °C; ESI(+) MS (m/z): 334.1

A switchable [2]rotaxane with two active alkenyl groups

• Xiu-Li Zheng,
• Rong-Rong Tao,
• Rui-Rui Gu,
• Wen-Zhi Wang and
• Da-Hui Qu

Beilstein J. Org. Chem. 2018, 14, 2074–2081, doi:10.3762/bjoc.14.181

• construct stimuli-responsive polymers and smart materials. Experimental General and materials 1H NMR and 13C NMR spectra were measured on a Bruker AV-400 spectrometer. The electronic spray ionization (ESI) mass spectra were tested on a LCT Premier XE mass spectrometer. Chemicals were used as received from

• Acros, Aldrich, Fluka, or Merck. All solvents were reagent grade, which were dried and distilled prior to use according to standard procedures. The molecular structures were confirmed via 1H NMR, 13C NMR and high-resolution ESI mass spectroscopy. The synthesis of compound 1, 2, 6, 7, 9 have already been

• ), 0.87 (t, J = 6.8 Hz, 9H); 13C NMR (CDCl3, 100 MHz, 298 K) δ 169.2, 167.8, 153.1, 141.3, 128.1, 105.6, 73.5, 69.2, 51.2, 44.1, 39.5, 31.9, 30.2, 29.70, 29.68, 29.66, 29.62, 29.56, 29.39, 29.36, 29.34, 29.31, 28.7, 26.4, 26.3, 26.07, 26.05, 22.7, 14.1; HRMS–ESI–TOF (m/z): [M + K]+ calcd for C51H93N5O5K

Synthesis and supramolecular self-assembly of glutamic acid-based squaramides

• Juan V. Alegre-Requena,
• Marleen Häring,
• Isaac G. Sonsona,
• Alex Abramov,
• Eugenia Marqués-López,
• Raquel P. Herrera and
• David Díaz Díaz

Beilstein J. Org. Chem. 2018, 14, 2065–2073, doi:10.3762/bjoc.14.180

• 2.5 instrument. Specific rotation calculations were made in chloroform or acetone employing a Jasco P-1020 polarimeter. ESI ionization method and mass analyzer type MicroTof-Q were used for HRMS measurements. 1H NMR spectra and 13C APT-NMR spectra were recorded at 300 MHz and 75 MHz, respectively

• ) ν: 3269, 2983, 1806, 1736, 1653, 1618, 1610, 1500, 1464, 1378, 1345, 1299, 1263, 1201, 1102, 1024; HRMS (ESI+) m/z: [M + Na]+ calcd for C14H19NNaO7, 336.1054; found, 336.1094. (S)-Diethyl 2-((2-(octadecylamino)-3,4-dioxocyclobut-1-en-1-yl)amino)pentanedioate (3): A solution of n-octadecylamine (8

• , 1203, 1021, 720; HRMS (ESI+) m/z: [M + Na]+ calcd for C31H54N2O6Na, 573.3874; found, 573.3840. (S)-2-((2-(Octadecylamino)-3,4-dioxocyclobut-1-en-1-yl)amino)pentanedioic acid (4): Squaramide 3 (1.2 g, 2.15 mmol) was dissolved in a 1:1 v/v MeOH/H2O mixture (40 mL) containing KOH (0.36 g, 6.45 mmol) at

Coordination-driven self-assembly vs dynamic covalent chemistry: versatile methods for the synthesis of molecular metallarectangles

• Li-Li Ma,
• Jia-Qin Han,
• Wei-Guo Jia and
• Ying-Feng Han

Beilstein J. Org. Chem. 2018, 14, 2027–2034, doi:10.3762/bjoc.14.178

• peaks was found. Again, significant downfield shifts of the pyridyl proton signals were observed, indicating the efficient self-assembly of the rhodium-based assembly (Figure 2a,b). Clear evidence for the formation of a discrete tetranuclear organometallic product was obtained from ESI mass spectrometry

• tetranuclear [4 + 4] condensation products 3a (Figure 1c) and 3b (Figure 2c) was observed, respectively. Complexes 3a and 3b were isolated in good yields, and their structures were confirmed by 1H NMR spectroscopy and ESI mass spectrometry. After establishing that the condensation reaction of 2 with amines is

• mg, 80%).1H NMR (400 MHz, DMSO-d6, ppm) δ 10.09 (s, 2H, -CHO), 8.89 (d, J = 5.0 Hz, 4H), 7.82 (d, J = 5.0 Hz, 4H), 1.55 (s, 30H, Cp*-H); HRMS–ESI (m/z): [2 − 2OTf]2+ calcd for C34H40O12N2F6S2Rh2, 390.0571; found, 390.0541. Synthesis of [Cp*4Rh4(μ-η2-η2-C2O4)2(L1)2](OTf)4 (3a) Method A: AgOTf (36 mg

An amphiphilic pseudo[1]catenane: neutral guest-induced clouding point change

• Tomoki Ogoshi,
• Tomohiro Akutsu and
• Tada-aki Yamagishi

Beilstein J. Org. Chem. 2018, 14, 1937–1943, doi:10.3762/bjoc.14.167

• ), 2.27 (t, 2H, alkyne) ppm; 13C NMR (125 MHz, CDCl3) δ 150.0, 149.8, 149.3, 129.1, 129.0, 128.6, 128.4, 115.6, 115.4, 115.2, 115.1, 71.9, 70.9, 70.8, 70.6, 70.4, 70.3, 68.3, 68.2, 68.1, 68.0, 59.0, 56.5, 29.7, 29.3 ppm; HRMS–ESI (m/z): [M + Na]+ calcd for C97H146NaO34, 1877.9593; found, 1877.9612

• , 149.6, 149.4 129.0, 128.6, 128.3, 124.3, 115.7, 115.0, 71.9, 70.8, 70.7, 70.6, 70.3, 68.4, 68.1, 67.8, 67.6, 59.0, 29.7, 29.0, 28.8, 28.5, 27.3, 24.5 ppm; HRMS–ESI (m/z): [M + 2Na]2+ calcd for C109H170N6Na2O34, 1076.5777; found, 1076.5635. Determination of association constants. In a similar manner as

A pyridinium/anilinium [2]catenane that operates as an acid–base driven optical switch

• Sarah J. Vella and
• Stephen J. Loeb

Beilstein J. Org. Chem. 2018, 14, 1908–1916, doi:10.3762/bjoc.14.165

• , 149.8, 147.6, 146.8, 140.5, 140.2, 129.9, 128.4, 127.9, 127.6, 120.8, 120.4, 113.1, 47.6; HRMS (ESI) m/z: [M + H]+ calcd for [C23H20N3]+, 338.1657; found, 338.1650. Synthesis of [7][OTf]4 [5][OTf]2 (0.400 g, 0.626 mmol) and 6 (2.61 g, 6.26 mmol) were dissolved in CH3CN (75 mL) and stirred at room

• = 6.1 Hz, 4H), 7.91 (s, 2H), 7.86 (d, 3J = 8.2 Hz, 4H), 7.71 (d, 3J = 8.2 Hz, 4H), 7.68 (d, 3J = 7.9 Hz, 2H), 7.67 (d, 3J = 8.2 Hz, 4H), 7.62 (d, 3J = 8.0 Hz, 4H), 7.57 (t, 3J = 7.9, 3J = 8.1 Hz, 2H), 7.54 (d, 3J = 8.2 Hz, 4H), 5.89 (s, 4H), 5.30 (br s, 4H), 4.66 (s, 4H); HRMS (ESI) m/z: [M − OTf

• ) to extract any remaining salts. The CH3NO2 layer was dried with anhydrous MgSO4 and then evaporated to yield [8DB24C8][OTf]6 as a yellow-orange solid. Yield 0.030 g, 12%; mp >210 °C (dec.); HRMS (ESI) m/z: [M − 2OTf]2+ calcd for [C113H103F12N7O20S4]2+, 1116.7969, found, 1116.7972; [M − 3OTf]3+ calcd

Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH

• Femke Beiroth,
• Tomas Koudelka,
• Thorsten Overath,
• Stefan D. Knight,
• Andreas Tholey and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163

• the LC–ESIMS conditions applied here, e.g., low pH and use of organic eluents in ion-paring reversed-phase chromatography, as well as under the ESI conditions employed, non-covalent bonding of the photolabile mannoside to FimH is unlikely to be observed. Due to the low labeling yield obtained, all our

• vapor lamp for 10 min. The protein solution was then investigated by ESI mass spectrometry. LC–MS methods Nano-LC–MS was performed on the U3000 nano-LC-UV system (Dionex, Idstein, Germany) coupled online to a LTQ Orbitrap Velos mass spectrometer equipped with LTQ Tune Plus 2.7.0 and XCalibur 2.2 (all

• –TOF mass spectrometer Bruker Biflex III with 19 kV acceleration voltage (matrix: 2,5-dihydroxybenzoic acid) and with a ESI–TOF MS spectrometer Applied Biosystems Mariner ESI–TOF 5280. UV data were obtained with the Perkin-Elmer UV–vis spectrometer Lambda 14 at 25 °C. All reactions and purification

Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae

• Bimal Koirala,
• Robert A. Hillman,
• Erin K. Tiwold,
• Michael A. Bertucci and
• Yftah Tal-Gan

Beilstein J. Org. Chem. 2018, 14, 1769–1777, doi:10.3762/bjoc.14.151

• obtained on an Agilent Technologies 6230 TOF LC/MS spectrometer. The samples were sprayed with a capillary voltage of 3500 V and the electrospray ionization (ESI) source parameters were as follows: gas temperature of 325 °C at a drying gas flow rate of 3 L/min at a pressure of 25 psi. Peptide synthesis

Synthesis and photophysical studies of a multivalent photoreactive Ru^II-calix[4]arene complex bearing RGD-containing cyclopentapeptides

• Sofia Kajouj,
• Lionel Marcelis,
• Alice Mattiuzzi,
• Adrien Grassin,
• Damien Dufour,
• Pierre Van Antwerpen,
• Didier Boturyn,
• Eric Defrancq,
• Mathieu Surin,
• Julien De Winter,
• Pascal Gerbaux,
• Ivan Jabin and
• Cécile Moucheron

Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150

• the ArH, ArCH2 and OPr group are differentiated. Moreover, complex 7 was also characterized by high-resolution mass spectrometry (HRMS). The ESI mass spectrum displays two intense signals at m/z 764.736 and m/z 1642.456 that are attributed respectively to the doubly charged 72+ and singly charged [7

• semi-preparative RP-HPLC (Scheme 2). The successful synthesis and purification of conjugate 9 was also confirmed by HRMS. Indeed, the ESI mass spectrum features several peaks corresponding to characteristic ions of different charge states at m/z 1421.577 (3+), 1066.434 (4+) and 853.556 (5+) that are

An amine protecting group deprotectable under nearly neutral oxidative conditions

• Shahien Shahsavari,
• Chase McNamara,
• Mark Sylvester,
• Emily Bromley,
• Savannah Joslin,
• Bao-Yuan Lu and
• Shiyue Fang

Beilstein J. Org. Chem. 2018, 14, 1750–1757, doi:10.3762/bjoc.14.149

• ; 13C NMR (100 MHz, CDCl3) δ 25.9, 27.4, 30.9, 61.0, 73.4 ppm; HRMS (ESI) m/z: [M + K]+ calcd for C7H14OS2K, 217.0123; found, 217.0121. 2-(1,3-Dithian-2-yl)propan-2-yl (4-nitrophenyl) carbonate (4): To a solution of 2-(1,3-dithian-2-yl)propan-2-ol (6.4 g, 36 mmol, 1 equiv) and pyridine (2.9 mL, 54 mmol

• , 6H), 1.81–1.91 (m, 1H), 2.11–2.18 (m, 1H), 2.92–2.95 (m, 4H), 4.98 (s, 1H), 7.38 (d, J = 9.2 Hz, 2H), 8.26 (d, J = 6.9 Hz, 2H) ppm; 13C NMR (100 MHz, CDCl3) δ 24.1, 25.7, 30.8, 56.2, 86.9, 121.9, 125.1, 145.2, 150.0, 155.5 ppm; HRMS (ESI) m/z: [M + K]+ calcd for C14H18O2S2K, 321.0385; found, 321.0404

• , 1452 cm−1; 1H NMR (400 MHz, CDCl3) δ 1.58 (s, 6H), 1.75–1.84 (m, 1H), 2.04–2.09 (m, 1H), 2.81–2.92 (m, 4H), 4.30 (d, J = 5.88 Hz, 2H), 5.00 (brs, 1H), 5.09 (s, 1H), 7.23–7.31 (m, 5H) ppm; 13C NMR (100 MHz, CDCl3) δ 25.1, 26.2, 31.2, 44.8, 57.6, 82.4, 127.5, 127.6, 128.7, 138.8, 155.3 ppm; HRMS (ESI) m

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

• identified by HRMS (ESI+, ACN + TFA). Under demanding thermal conditions, the complete amination of cyanuric chloride by D-N

  NH gave the G-2 dendrimer 4 with satisfactory yield. By contrast, treatment of 1,3,5-tris(bromomethyl)benzene with D-N

  NH (3 equiv, 72 h in refluxing 1,4-dioxane in the presence of

• Scientific) instrument which was externally calibrated using the manufacturer’s ESI(+) calibration mix. The samples were introduced into the spectrometer by direct infusion. DFT calculations The full geometry optimisation of compounds 2a, 3, 7a and 7b were carried out using DFT level of theory considering

A conformationally adaptive macrocycle: conformational complexity and host–guest chemistry of zorb[4]arene

• Liu-Pan Yang,
• Song-Bo Lu,
• Arto Valkonen,
• Fangfang Pan,
• Kari Rissanen and
• Wei Jiang

Beilstein J. Org. Chem. 2018, 14, 1570–1577, doi:10.3762/bjoc.14.134

• ZB4 were observed in the NMR spectra (Figures S3–S7 in Supporting Information File 1). The ESI mass spectra of equimolar mixtures of guests 9+ and 10+ and ZB4 were obtained (Figures S9 and S10 in Supporting Information File 1) and the predominant peaks were assigned to 1:1 complexes after losing PF6

Lanyamycin, a macrolide antibiotic from Sorangium cellulosum, strain Soce 481 (Myxobacteria)

• Lucky S. Mulwa,
• Rolf Jansen,
• Dimas F. Praditya,
• Kathrin I. Mohr,
• Patrick W. Okanya,
• Joachim Wink,
• Eike Steinmann and
• Marc Stadler

Beilstein J. Org. Chem. 2018, 14, 1554–1562, doi:10.3762/bjoc.14.132

• acquisition, processing, and spectral analysis were performed with standard Bruker software and ACD/NMR workbook. Chemical shifts are given in parts per million (ppm), and coupling constants in hertz (Hz). HRESIMS data were recorded on a Maxis ESI TOF mass spectrometer (Bruker Daltonics); molecular formulas

Enantioselective phase-transfer catalyzed alkylation of 1-methyl-7-methoxy-2-tetralone: an effective route to dezocine

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 1421–1427, doi:10.3762/bjoc.14.119

• determined on a Büchi Melting Point M-565 apparatus and are uncorrected. 1H and 13C NMR spectra were recorded using a Bruker 400 MHz spectrometer with TMS as an internal standard. Mass spectra were recorded with a Q-TOF mass spectrometer using electrospray positive ionization (ESI+). The enantiomeric ratio

• –0.86 (m, 2H); 13C NMR (100 MHz, CDCl3/TMS) δ 214.55,158.74, 143.40, 129.00, 128.16, 112.44, 111.33, 55.32, 51.80, 40.13, 38.57, 33.71, 32.42, 28.47, 27.60, 27.35, 24.28; MS (ESI+) m/z: 339.00 [M + H]+. The above-obtained product underwent subsequent cyclization, oximation and reduction according to the

Design and biological characterization of novel cell-penetrating peptides preferentially targeting cell nuclei and subnuclear regions

• Anja Gronewold,
• Mareike Horn and
• Ines Neundorf

Beilstein J. Org. Chem. 2018, 14, 1378–1388, doi:10.3762/bjoc.14.116

• /v) was added for 3 h. Afterwards, the peptides were precipitated in ice cold diethyl ether, washed and lyophilized from water/tert-butanol (3:1 v/v). Then, peptides were analyzed by RP-HPLC/ESI-MS on a Kinetex C18 column (100 × 4.6 mm; 2.6 μm/100 Å) using linear gradients of 10–60% B in A (A = 0.1

London dispersion as important factor for the stabilization of (Z)-azobenzenes in the presence of hydrogen bonding

• Andreas H. Heindl,
• Raffael C. Wende and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 1238–1243, doi:10.3762/bjoc.14.106

• , 129.6, 128.7, 122.6, 120.5, 40.7*, 39.5*, 27.2; HRMS (ESI) m/z: [M + Na]+ calcd, 583.3043; found, 583.3043. *identified by HSQC and HMBC spectroscopy. a) Optimized geometry of open conformer (R,S)-4 c0. b) NCI plot of the most stable conformer of (R,S)-4 (green and blue isosurfaces indicate attractive

Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery

• Sabine Schuster,
• Beáta Biri-Kovács,
• Bálint Szeder,
• Viktor Farkas,
• László Buday,
• Zsuzsanna Szabó,
• Gábor Halmos and
• Gábor Mező

Beilstein J. Org. Chem. 2018, 14, 756–771, doi:10.3762/bjoc.14.64

• described above. Peaks were detected at 220 nm. Mass spectrometry Electrospray ionization (ESI) mass spectrometric analyses were carried out on an Esquire 3000+ ion trap mass spectrometer (Bruker Daltonics, Bremen, Germany). Spectra were acquired in the 50–2500 m/z range. Samples were dissolved in a mixture