Novel carbazole–pyridine copolymers by an economical method: synthesis, spectroscopic and thermochemical studies

• Aamer Saeed,
• Madiha Irfan and
• Shahid Ameen Samra

Beilstein J. Org. Chem. 2011, 7, 638–647, doi:10.3762/bjoc.7.75

• : 84.3%, H: 5.9%, N: 7.1%. Poly{[N-butylcarbazole-3,6-diyl][4-(3-nitrophenyl)pyridine-2,6-diyl]} (P1b) Yellow powder; yield: 49%; IR (KBr, υ/cm−1): 3035, 2930, 2890, 1656, 1585, 1523, 1345, 1145, 800; 1H NMR (CDCl3, 300 MHz): δ 8.96 (s, Ar-8), 8.58 (s, Ar-7), 8.27 (m, Ar-H), 8.0 (d, J = 7.8 Hz, Ar-5

• , 129.0, 127.3, 126.2, 120.7, 118.1, 116.5, 110.5, 35.2, 30.1, 29.2, 28.7, 27.2, 21.9, 14.8; Elemental analysis: Calcd C: 86.5%, H: 6.9%, N: 6.5%; found C: 83.3%, H: 6.7%, N: 6.1%. Poly{[N-octylcarbazole-3,6-diyl][4-(3-nitrophenyl)pyridine-2,6-diyl]} (P2b) Yellow powder; yield: 46%; IR (KBr, υ/cm−1): 3070

CuCl-catalyzed aerobic oxidation of 2,3-allenols to 1,2-allenic ketones with 1:1 combination of phenanthroline and bipyridine as ligands

• Shuxu Gao,
• Yu Liu and
• Shengming Ma

Beilstein J. Org. Chem. 2011, 7, 396–403, doi:10.3762/bjoc.7.51

• ), 0.76), 262 (M+ (35Cl), 2.08), 139 (100); IR (neat) 2927, 2857, 1931, 1654, 1590, 1460, 1397, 1274, 1091 cm−1; HRMS-EI (m/z) calcd for C16H19O35Cl+ [M+]: 262.1124; found: 262.1130. 2-Hexyl-1-(4'-nitrophenyl)buta-2,3-dien-1-one (2e) The reaction of 1,10-phenanthroline (5.5 mg, 0.03 mmol), 2,2'-bipyridine

• (4.7 mg, 0.03 mmol), CuCl (5.9 mg, 0.06 mmol), K2CO3 (20.8 mg, 0.15 mmol), dry toluene (1.5 mL), DBAD (13.9 mg, 0.06 mmol), and 2-hexyl-1-(4-nitrophenyl)buta-2,3-dien-1-ol (82.7 mg, 0.3 mmol)/dry toluene (1.5 mL) afforded 2e (51.4 mg, 63%) (eluent: petroleum ether/diethyl ether = 20:1): liquid; 1H NMR

Anion–π interactions influence pK_a values

• Christopher J. Cadman and
• Anna K. Croft

Beilstein J. Org. Chem. 2011, 7, 320–328, doi:10.3762/bjoc.7.42

• -nitrophenyl)-1-naphthol (2): mp 135–135.5 °C; 1H NMR δ = 7.02 (d, 2H, J = 9.15 Hz), 7.17 (s, 1H), 7.50 (m, 3H), 7.79 (d, 1H, J = 8.5 Hz), 7.93 (d, 2H, J = 9.15 Hz), 8.20 (d, 2H, J = 9.45 Hz) ppm; 13C NMR δ = 116.6, 121.6, 125.8, 125.9, 126.1, 126.7, 126.9, 127.0, 128.2, 135.2, 150.4 ppm; IR (nujol mull) ν

Surfactant catalyzed convenient and greener synthesis of tetrahydrobenzo[a]xanthene-11-ones at ambient temperature

• Pravin V. Shinde,
• Amol H. Kategaonkar,
• Bapurao B. Shingate and
• Murlidhar S. Shingare

Beilstein J. Org. Chem. 2011, 7, 53–58, doi:10.3762/bjoc.7.9

• (50 MHz, CDCl3): δ 27.1, 29.3, 32.5, 34.3, 41.9, 50.9, 113.1, 116.8, 117.3, 123.9, 125.0, 127.2, 128.7, 129.4, 130.2, 131.5, 131.9, 132.6, 143.3, 145.1, 150.8, 164.2, 196.9; IR (KBr, cm−1): v 2952, 1648, 1597, 1373, 1231, 1184, 823; ES-MS: 389.14 [M+], 391.13 [M+ + 2]. 12-(2-nitrophenyl)-9,9-dimethyl

Anthracene appended pyridinium amide–urea conjugate in selective fluorometric sensing of L-N-acetylvaline salt

• Kumaresh Ghosh,
• Tanmay Sarkar and
• Asoke P. Chattopadhyay

Beilstein J. Org. Chem. 2010, 6, 1211–1218, doi:10.3762/bjoc.6.139

• with 4-nitrophenyl isocyanate (obtained from 4-nitroaniline by reaction with triphosgene in dry THF) in dry THF to give urea derivative 5. Subsequent reaction of 5 with 9-chloromethylanthracene under refluxing conditions in dry CH3CN gave the chloride salt 6. Anion exchange of the salt 6 with NH4PF6

• -N-acetylvaline salt than with L-N-acetylalanine. This is attributed to the formation of a charge transfer complex between the excited state of anthracene and the electron deficient nitrophenyl urea during the interaction process. We believe that this characteristic feature with L-N-acetylvaline is

• nitrophenyl urea as represented in Figure 4a, takes place. This component coexists with the other components contributing large preexponential factor to the total fluorescence. This finding was not observed with L-N-acetylalanine or L-N-acetylproline salts (Table 1). Neither was this observed when the

Catalysis: transition-state molecular recognition?

• Ian H. Williams

Beilstein J. Org. Chem. 2010, 6, 1026–1034, doi:10.3762/bjoc.6.117

• relative free energy difference of about 20 kJ mol−1, by means of the OYHY…Oring hydrogen bond [23]. A two-dimensional PMF computed for 4-nitrophenyl β-xylobioside (the substrate employed in the experimental kinetics studies) with BCX using the same AM1/OPLS-AA hybrid potential, as a function of

En route to photoaffinity labeling of the bacterial lectin FimH

• Thisbe K. Lindhorst,
• Michaela Märten,
• Andreas Fuchs and
• Stefan D. Knight

Beilstein J. Org. Chem. 2010, 6, 810–822, doi:10.3762/bjoc.6.91

• the second case, a closed-gate conformation of FimH was used for the modeling [8]. This led to somewhat different predictions, as expected, however, the same trends were revealed for ligands 1–3 and 5 in comparison with the well-known standard ligands methyl α-D-mannoside (MeMan) and p-nitrophenyl α-D

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• . Conversion to 4-nitrophenyl trifluoromethyl sulfide (60% yield) requires prolonged irradiation in a quartz ampoule at 30–45 °C [143]. The length of the perfluoroalkyl iodide chain has no influence, although lower yields were observed using CF3I in comparison with other iodoperfluoroalkanes. A branching RFI

Kinetic studies and predictions on the hydrolysis and aminolysis of esters of 2-S-phosphorylacetates

• Milena Trmčić and
• David R. W. Hodgson

Beilstein J. Org. Chem. 2010, 6, 732–741, doi:10.3762/bjoc.6.87

• shortfalls, 2-S-(5′-thiophosphoryluridine)acetic acid esters were prepared using p-nitrophenyl bromoacetate or m-nitrophenyl bromoacetate in combination with uridine-5′-monophosphorothioate. Kinetics of hydrolysis and aminolysis of the resulting p- and m-nitrophenyl 2-S-(5′-thiophosphoryluridine)acetates

• were determined by monitoring the formation of phenolate ions spectrophotometrically as a function of pH. The p- and m-nitrophenyl 2-S-(5′-thiophosphoryluridine)acetates showed similar reactivity profiles despite the significant difference in the pKaH values of their nitrophenolate leaving groups. Both

• were used to predict leaving group pKa values that could lead to improved selectivity towards aminolysis while retaining reasonable reaction times. Conclusions: Both p- and m-nitrophenyl 2-S-(5′-thiophosphoryluridine)acetates show some selectivity towards aminolysis over hydrolysis, with the m

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• coupling of 1-(3-nitrophenyl)-2-(pyrrolidin-1-yl)diazene and phenylboronic acid as a model reaction (Scheme 2). As described for the homogeneous catalytic conditions [29], a Lewis acid was essential for the formation of the biphenyl products. Without BF3·OEt2, no diaryl product was observed whatsoever

• improved yields (Table 2, entry 6). Table 3 shows the effect of the molar ratio of phenylboronic acid to 1-(3-nitrophenyl)-2-(pyrrolidin-1-yl)diazene on the reaction yield. A yield of 77% was obtained when the molar ratio was 1.25 (Table 3, entry 1). The yield of the corresponding biaryl product increased

• Suzuki–Miyaura cross-coupling reactions of 1-(3-nitrophenyl)-2-(pyrrolidin-1-yl)diazene and phenylboronic acid was investigated (Table 4). The catalyst could be re-used eight times and still retained high activity after separation, washing and drying under vacuum, under the same reaction conditions. To

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• ). Interestingly, the method was developed for the synthesis of heteroaromatic diarylsulfonium salts. Thus, p-nitrophenyl trifluoromethyl sulfide was reacted first with xenon difluoride in the absence of solvent and then with boron trifluoride. The addition of an electron-rich heterocycle gave products 28 and 29

Chemical synthesis using enzymatically generated building units for construction of the human milk pentasaccharides sialyllacto-N-tetraose and sialyllacto-N-neotetraose epimer

• Dirk Schmidt and
• Joachim Thiem

Beilstein J. Org. Chem. 2010, 6, No. 18, doi:10.3762/bjoc.6.18

• p-nitrophenyl β-galactopyranoside and β-galactosidase (Bovin testes). The subsequent transsialylation was carried out with p-nitrophenyl sialoside (pNp-αNeu5Ac) and either sialidase from Salmonella typhimurium or from Newcastle disease virus [7]. Recently, a more effective higher yielding transfer

• a down field shifted doublet for H-4′ at δ 5.37 (J3′4′ = 2.9 Hz). A similar approach was employed for the synthesis of the protected epimer of sialyllacto-N-neotetraose 14. β-Galactosylation of 2-azidothioglucoside with p-nitrophenyl β-galactopyranoside and β-galactosidase (Bacillus circulans) gave

Synthesis of indolo[3,2-b]carbazole-based new colorimetric receptor for anions: A unique color change for fluoride ions

• Ajit Kumar Mahapatra,
• Giridhari Hazra and
• Prithidipa Sahoo

Beilstein J. Org. Chem. 2010, 6, No. 12, doi:10.3762/bjoc.6.12

• ][24][25][26][27][28], there is a paucity of reports on selective naked-eye chemosensors for fluoride [29][30][31]. Nitrophenyl, nitronaphthalene urea [32][33][34], naphthalene triphenyl-phosphonium [35], benzimidazolyl pyridine [36][37] and oxidized bis(indolyl)methane [38] as signal units for

Synthesis of rigidified flavin–guanidinium ion conjugates and investigation of their photocatalytic properties

• Harald Schmaderer,
• Mouchumi Bhuyan and
• Burkhard König

Beilstein J. Org. Chem. 2009, 5, No. 26, doi:10.3762/bjoc.5.26

• the presence of sacrificial electron donor substrates, such as aliphatic amines, flavins can photoreduce nitro arenes to anilines under blue light irradiation (Scheme 4). 4-Nitrophenyl phosphate was used as a substrate for photoreduction in water and in acetonitrile. The results summarized in Table 2

• )2, mono-Boc guanidine, CH2Cl2, rt, 20 h, 58–82%, (iii) HCl/Et2O, CH2Cl2/CHCl3, rt, 24 h, 83–90%. Oxidative photocleavage of dibenzyl phosphate. Photoreduction of 4-nitrophenyl phosphate. Photo Diels–Alder-reaction of anthracene with N-methyl-maleinimide. Oxidative photocleavage of dibenzyl phosphate

New diarylmethanofullerene derivatives and their properties for organic thin- film solar cells

• Daisuke Sukeguchi,
• Surya Prakash Singh,
• Mamidi Ramesh Reddy,
• Hideyuki Yoshiyama,
• Rakesh A. Afre,
• Yasuhiko Hayashi,
• Hiroki Inukai,
• Tetsuo Soga,
• Shuichi Nakamura,
• Norio Shibata and
• Takeshi Toru

Beilstein J. Org. Chem. 2009, 5, No. 7, doi:10.3762/bjoc.5.7

• the electron-withdrawing nature of the (methoxycarbonyl)phenyl, cyanophenyl, nitrophenyl, (methylsulfonyl)phenyl, and (trifluoromethylsulfonyl)phenyl groups attached to the cyclopropane ring, enough to compensate the opposite effect of the electron-donating mono-, bis-, or tris(octyloxy)phenyl group

• -nitrophenyl, (methylsulfonyl)phenyl, and (trifluoromethylsulfonyl)phenyl groups, taking a P3HT:PCBM-blended cell as a reference, were examined. Table 2 shows the current density–voltage (J–V) characteristic parameters of the devices structured from P3HT:diarylmethanofullerene derivatives 1a–1k, 2 and

• work as acceptors, probably because of their low solubility in ODCB. The bis(methoxycarbonyl)phenyl- and cyanophenyl-substituted methanofullerenes 1f and 1g showed good PCE, whereas nitrophenyl-substituted methanofullerenes 1h and 1i did not work as acceptors. (Methoxycarbonyl)phenylmethano-C70

Reduction of arenediazonium salts by tetrakis(dimethylamino)ethylene (TDAE): Efficient formation of products derived from aryl radicals

• Mohan Mahesh,
• John A. Murphy,
• Franck LeStrat and
• Hans Peter Wessel

Beilstein J. Org. Chem. 2009, 5, No. 1, doi:10.3762/bjoc.5.1

• %; (d) N-(2-nitrophenyl)methanesulfonamide (25a), DIAD, PPh3, THF, 0 °C to r.t., 1 h, 98%; (e) TBAF, THF, r.t., 20 min, 90%; (f) NBS, PPh3, CH2Cl2, −25 °C, 20 min, then 37, −25 °C to r.t., 40 min, 96%; (g) PhSH, NaH, THF, 0 °C to r.t., 1 h, then 38, r.t., 12 h, 86%; (h) NaIO4, H2O, MeOH, r.t., 76 h, 73

The role of an aromatic group in remote chiral induction during conjugate addition of α-sulfonylallylic carbanions to ethyl crotonate

• Shlomo Levinger,
• Ranjeet Nair and
• Alfred Hassner

Beilstein J. Org. Chem. 2008, 4, No. 32, doi:10.3762/bjoc.4.32

• cyanoborohydride in an acidic medium. Phenyl-, (4-nitrophenyl)- and (1-naphthyl)ethylamines 6a, c, e are commercial. Interestingly, the 9-anthryl nucleus in both primary amine 6h and its allyl sulfone congener 1h shows a peculiar 1H NMR spectrum: a broad signal representing both protons 1 and 8 in the first

New acylides: synthesis of 3-O-[γ-(4-oxo-2-aryl- thiazolidin- 3-yl)butyryl]erythromycin A derivatives

• Deepa Pandey,
• Wahajul Haq and
• Seturam B. Katti

Beilstein J. Org. Chem. 2008, 4, No. 14, doi:10.3762/bjoc.4.14

• -aryl-thiazolidin-3-yl)butyryl]-6-O-methylerythromycin A derivatives 4a–f (Method A); R = 4a: phenyl, 4b: 4-chlorophenyl, 4c: 4-fluorophenyl, 4d: 4-methoxyphenyl, 4e: 4-nitrophenyl and 4f: 4-quinolyl. Synthesis of 3-O-[γ-(4-oxo-2-aryl-thiazolidin-3-yl)butyryl]erythromycin A derivatives 4a–f (Method B

Microwave assisted synthesis of triazoloquinazolinones and benzimidazoquinazolinones

• Aboul-Fetouh E. Mourad,
• Ashraf A. Aly,
• Hassan H. Farag and
• Eman A. Beshr

Beilstein J. Org. Chem. 2007, 3, No. 11, doi:10.1186/1860-5397-3-11

• ] Other triazoloquinazolines were obtained from 2'-azidoacetophenone and as well as 2-azidobenzonitrile. [11] Quinazolines were also obtained in moderate yields by an intermolecular reductive N-heterocyclization of 2-nitro-benzaldehydes or 2-nitrophenyl ketones with formamide catalyzed by a combination of

The Elbs and Boyland- Sims peroxydisulfate oxidations

• E. J. Behrman

Beilstein J. Org. Chem. 2006, 2, No. 22, doi:10.1186/1860-5397-2-22

• , although they obtained evidence for a peroxide, isolated only phenol (in substantial yield). Heller and Weiler [18] investigated a more stable analog, namely p-nitrophenyl hydroperoxide formed by ipso displacement of a nitro group from p-dinitrobenzene by the hydrogen peroxide anion.p-Nitrophenyl

Asymmetric aza-Diels- Alder reaction of Danishefsky's diene with imines in a chiral reaction medium

• Bruce Pégot,
• Olivier Nguyen Van Buu,
• Didier Gori and
• Giang Vo-Thanh

Beilstein J. Org. Chem. 2006, 2, No. 18, doi:10.1186/1860-5397-2-18

• was observed in the case of p-nitrophenyl (Table 3, entry 4, R = p-NO2C6H4,). This is due to hydrogen bond formation between the OH group of the chiral ionic liquid and the NO2 function of the substrate. A similar decrease in asymmetric induction was observed by our group in the mechanistically