Dendrimer Folding in Aqueous Media: An Example of Solvent-Mediated Chirality Switching (original) (raw)

J. Serb. Chem. Soc. 82 (3) 241–251 (2017).pdf

Journal of the Serbian Chemical Society , 2017

A series of novel bis(1,2,3-triazoles) derivatives 7a–m were synthesized by the 1,3-dipolar cycloaddition (click-reaction) of 1-methyl-3,5-bis(2-(prop-2-yn-1-yloxy)phenyl)-4,5-dihydro-1H-pyrazole (5) with various aralkyl azides 6a–m in the presence of sodium ascorbate and copper sulphate with good yields. The required precursor 5 was synthesized by reacting (E)-1,3-bis(2-hydroxyphenyl)prop-2-en-1-one (3) with methylhydrazine hydrate via 2,2′-(1-methyl-4,5-dihydro-1H-pyrazole-3,5-diyl)diphenol 4, followed by reaction with propargyl bromide. The homogeneity of all the newly synthesized compounds was checked by TLC. The IR, NMR, mass spectral data and elemental analysis were in accord with the assigned structure. The title compounds were evaluated for their antibacterial activity against various bacterial strains, i.e., Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis; compounds 7f–7h and 7j were found to be moderately active against the bacteria, when compared with that of the standard drug. Furthermore, the same library of compounds was evaluated for their antioxidant activity using the nitric oxide radical scavenging activity. The results of the study showed that compounds 7e–7h and 7k–7m showed good radical scavenging activity.

Reactive trityl derivatives: stabilised carbocation mass-tags for life sciences applications

Organic & Biomolecular Chemistry, 2008

Instrumentation. 500 MHz 1 H and 125.7 MHz 13 C NMR spectra were recorded on a Bruker DRX-500 spectrometer and referenced to CDCl 3 (7.25 ppm) and DMSO-d 6 (2.50 ppm). 1 H-13 C gradient-selected HMQC and HMBC spectra were obtained by using 2048 (t 2 )×256 (t 1 ) complex point data sets, zero filled to 2048 (F 2 )×1024 (F 1 ) points. The spectral widths were 13 ppm and 200 ppm for 1 H and 13 C dimensions, respectively. HMBC spectra were measured with 50 ms delay for evolution of long-range couplings. (MA)LDI-TOF mass spectra were obtained using a Voyager Elite Biospectrometry Research Station (PerSeptive Biosystems, Vestec Mass Spectrometry Products) in a positive ion mode. EI-TOF HRMS and ESI-TOF HRMS spectra in positive ion mode were obtained using Micromass LCT reflection TOF mass spectrometer. Analytical thin-layer chromatography was performed on the Kieselgel 60 F 254 precoated aluminium plates (Merck), spots were visualised under UV light (254 nm). Column chromatography was performed on silica gel (Merck Kieselgel 60 0.040-0.063 mm). Reagents and solvents. Reagents obtained from commercial suppliers were used as received. 4-Hydroxy-4′-methoxybenzophenone (3), [1] Pd(PPh 3 ) 4 , tert-butyl 6-bromohexanoate, were prepared as described. Solvents were mainly HPLC grade and used without further purification unless otherwise noted. DCM was always used freshly distilled over CaH 2 . THF was distilled over powdered LiAlH 4 or over sodium benzophenone ketyl and stored over 4Å molecular sieves under nitrogen. DMF was freshly distilled under reduced pressure. OH O O O O O Cl(CH 2 ) 3 CO 2 Bu t MeONa / HMPA 75%

Russ. J. Org. Chem. 2010, 46, 1192-1206 (Zhurnal Organicheskoi Khimii, 2010, 46, 1191-1204)

Partly hydrogenated 2-[5-methyl(bromo, nitro)furan-2-yl]-substituted furo [3,2-c]quinolines, pyrano-[3,2-c]quinolines, and 4-ethoxyquinolines were synthesized by the imino Diels-Alder (Povarov) reaction. Cycloadditions of these compounds with maleic, citraconic, and dibromomaleic anhydrides, as well as with acryloyl, methacryloyl, and cinnamoyl chlorides led to the formation of substituted epoxyisoindolo[2,1-a]quinolines and -quinolinecarboxylic acids. Oxidation of the double C=C bond in the adducts, esterification of the carboxy group, and aromatization of the 7-oxabicycloheptene fragment were accomplished. s (3H, COMe), 2.97 d.d.q (1H, 3a-H, J 3a, 4 = 3.2, J 3a, 9b = 7.6, J 3a, 3 = 8.2 Hz), 3.74 d.t -H, 2 J = 3 J = 8.6 Hz), 3.82 q (1H, 2-H, 2 J = 8.4, 3 J = 4.4 Hz), 4.44 br.s (NH), 4.81 d (1H, 4-H, J 3a, 4 = 3.2 Hz), 5.22 d (1H, 9b-H, J 3a, 9b = 7.6 Hz), 6.30 d.d (1H, 3′-H, 4 J = 0.8, 3 J = 3.2 Hz), 6.38 d.d (1H, 4′-H, J 5′, 4′ = 1.8, J 4′, 3′ = 3.2 Hz), 6.59 d (1H, 6-H, J 6, 7 = 8.5 Hz), 7.40 d.d (1H, 5′-H, J 5′, 4′ = 1.8, J 5′, 3′ = 0.8 Hz), 7.74 d.d (1H, 7-H, J 7, 9 = 2.0, J 6, 7 = 8.5 Hz), 7.97 d (1H, 9-H, J 7, 9 = 2.0 Hz). Mass spectrum, m/z (I rel , %): 283 (100) [M] + , 268 (22), 254 (13), 238 (90), 210 (9), 198 (6), 172 (15), 167 (5), 103 (5), 81 (6), 43 (7). Found, %: C 72.31; H 6.21; N 4.78. C 17 H 17 NO 3 . Calculated, %: C 72.07; H 6.05; N 4.94. M 283.12. 1-H), 2.05 m (1H, 1-H), 2.34 d.d.d (1H, exo-10-H, J 9a, exo-10 = 3.9, J exo-10, 11 = 4.8, 2 J = 12.1 Hz), 2.76 d.d (1H, 9a-H, J 9a, exo-10 = 3.9, J 9a, endo-10 = 9.2 Hz), 3.21 m (1H, 13c-H), 3.89-4.03 m (2H, 2-H), 4.47 d (1H, 13b-H, J 13b, 13c = 3.4 Hz), 5.17 d.d (1H, 11-H, J exo-10, 11 = 4.8, J 11, 12 = 1.5 Hz), 5.37 d (1H, 3a-H, J 3a, 13c = 8.2 Hz), 6.47 d.d (1H, 12-H, J 11, 12 = 1.5, J 12, 13 = 5.8 Hz), 6.57 d (1H, 13-H, J 12, 13 = 5.8 Hz), 6.98 d.d (1H, 6-H, J 5, 6 = 7.7, J 4, 6 = 1.5 Hz), 7.21 t (1H, 5-H, J 4, 5 = J 5, 6 = 7.7 Hz), 7.22 d.d (1H, 4-H, J 4, 5 = 7.7, J 4, 6 = 1.5 Hz), 9.45 s (OH); cis isomer: 1.77 d.d (1H, endo-10-H, J 9a, endo-10 = 9.2, 2 J = 11.6 Hz), 1.90 m (1H, 1-H), 2.13 m (1H, 1-H), 2.17 d.d.d (1H, exo-10-H, J 9a, exo-10 = 3.9, J exo-10, 11 = 4.4, 2 J = 11.6 Hz), 2.55 d.d (1H, 9a-H, J 9a, exo-10 = 3.9, J 9a, endo-10 = 9.2 Hz), 3.15 m (1H, 13c-H), 3.89-4.03 m (2H, 2-H), 4.52 d (1H, 13b-H, J 13b, 13c = 2.9 Hz), 5.14 d.d (1H, 11-H, J exo-10, 11 = 4.4, J 11, 12 = 1.5 Hz), 5.35 d (1H, 3a-H, J 3a,13c = 8.2 Hz), 6.53 d.d (1H, 12-H, J 11, 12 = 1.5, J 12, 13 = 5.8 Hz), 6.58 d (1H, 13-H, J 12, 13 = 5.8 Hz), 7.00 d.d (1H, 6-H, J 5, 6 = 7.7, J 4, 6 = 1.5 Hz), 7.29 t (1H, 5-H, J 4, 5 = J 5, 6 = 7.7 Hz), 7.36 d.d (1H, 4-H, J 4, 5 = 7.7, J 4, 6 = 1.5 Hz), 9.45 s (OH). Mass spectrum, m/z (I rel , %): 311 (31) [M] + , ,13b,13c-hexahydro-3aH-furo[3,2-c]isoindolo[2,1-a]quinolin-9(9aH)-one (VIIId) (mixture of trans and cis isomers at a ratio of 1 : 1. Yield 87%, mp 157-158°C (from hexane-ethyl acetate), R f 0.62, 0.91 (hexane-ethyl acetate, 1 : 1). IR spectrum: ν 1691 cm -1 (C=O). 1 H NMR spectrum (CDCl 3 ), δ, ppm: trans isomer: 1.69 s (3H, Me), 1.80 d.d (1H, endo-10-H, J 9a, endo-10 = 9.0, 2 J = 11.8 Hz), 1.86 m (1H, 1-H), 2.07 d.d (1H, exo-10-H, J 9a, exo-10 = 3.5, 2 J = 11.8 Hz), 2.65 m (1H, 1-H), 2.89 m (1H, 13c-H), 3.72 d.d (1H, 9a-H, J 9a, exo-10 = 3.5, J 9a, endo-10 = 9.0 Hz), 3.86-3.95 m (2H, 2-H), 4.42 d (1H, 13b-H, J 13b, 13c = 2.7 Hz), 5.36 d (1H, 3a-H, J 3a,13c = 8.2 Hz), 6.33 d ( 1H, J 12, 13 = 5.7 Hz), 6.54 d (1H, J 12, 13 = 5.7 Hz), 7.17 d.t (1H, J 4, 5 = J 5, 6 = 7.7, J 5, 7 = 1.1 Hz), 7.32 d.d (1H, J 5, 6 = 7.7, J 6, 7 = 8.1 Hz), 7.42 br.d (1H, J 4, 5 = 7.7 Hz), 8.03 d.d (1H, J 5, = 1.1, J 6, 7 = 8.1 Hz); cis isomer: 1.64 s (3H, Me), 1.71 d.d (1H, endo-10-H, J 9a, endo-10 = 8.7, 2 J = 11.8 Hz), 1.86 m (1H, 1-H), 1.99 d.d (1H, exo-10-H, J 9a, exo-10 = 3.6, 2 J = 11.8 Hz), 2.70 m (1H, 1-H), 3.11 m (1H, 13c-H), 3.66 d.d (1H, 9a-H, J 9a, exo-10 = 3.6, J 9a, endo-10 = 8.7 Hz), 3.84 m (2H, 2-H), 4.70 d (1H, 13b-H, J 13b, 13c = 2.5 Hz), 5.24 d (1H, 3a-H, J 3a, 13c = 7.2 Hz), 6.30 d (1H, 13-H, J 12, 13 = 5.7 Hz), 6.44 d (1H, 12-H, J 12, 13 = 5.7 Hz), 7.11 d.t (1H, 5-H, J 4, 5 = J 5, 6 = 7.7, J 5, 7 = 1.1 Hz), 7.24 d.d (1H, 6-H, J 5, 6 = 7.7, J 6, 7 = 8.4 Hz), 7.48 br.d (1H, 4-H, J 4, 5 = 7.7 Hz), 8.66 d.d (1H, 7-H, J 5, 7 = 1.1, J 6, 7 = 8.4 Hz). Mass spectrum, m/z (I rel , %): 309 (18) [M] + ,

J. Org. Chem., 2017, 82 (18), pp 9751–

A series of scarce fulleropyrrolines were synthesized via DMAP-mediated one-step reaction of [60]fullerene with commercially inexpensive aromatic aldehydes and arylmethanamines in the absence or presence of manganese(III) acetate. In the case of aminodiphenylmethane, novel 2,5,5-trisubstituted fulleropyrrolines could be easily obtained without the addition of manganese(III) acetate. As for arylmethanamines without α-substitutions, the addition of manganese(III) acetate was required to suppress the formation of fulleropyrrolidines, in order to generate the desired 2,5disubstituted fulleropyrrolines. Two tautomers were produced as expected when different aryl groups (Ar 1 ≠ Ar 2 ) from aromatic aldehydes and arylmethanamines were employed in the synthesis. A plausible reaction mechanism for the formation of fulleropyrrolines is proposed. a All reactions were performed in ODCB (6 mL) under air conditions at 180°C unless otherwise indicated, molar ratio refers to C 60 /1/2a/DMAP = 1:5:5:2. b Isolated yield, those in parentheses were based on consumed C 60 . a Unless otherwise indicated, all reactions were performed in ODCB (6 mL) under air conditions. b Molar ratio refers to C 60 /1a/2a/metal oxidant/ base. c Isolated yield; those in parentheses were based on consumed C 60 . d The reaction was conducted under nitrogen conditions. e 0.5 g of C 60 dissolved in 84 mL of ODCB was used to prepare 5a on a larger scale.

J. Org.Chem. 1983, 48, 995-1000.pdf

J. Org. Chem. the relative ease of formation of the intermediates (IB > I H ) , while the slopes (greater a t lower pH) may reflect the relative ease of trapping of the two intermediates.

Accelerated Growth of Dendrimers via Thiol-Ene and Esterification Reactions

Macromolecules, 2010

By taking advantage of the orthogonal nature of thiol-ene coupling and anhydride based esterification reactions, a facile and chemoselective strategy to dendritic macromolecules has been developed. The ability to interchange growth steps based on thiol-ene and anhydride chemistry allows the synthesis of fifth-generation dendrimers in only five steps and under benign reaction conditions. In addition, the presented coupling chemistries eliminate the traditional need for protection/deprotection steps and afford dendrimers in high yield and purity. The modularity of this strategy coupled with the latent reactivity of the alkene/hydroxyl chain ends was demonstrated by using different cores (alkene and hydroxyl functional), various AB 2 and CD 2 monomers and a range of chain end groups. As a result, three dendritic libraries were prepared which exhibited tunability of both the chemical functionality and physical properties including the fabrication of PEG hydrogels. *Corrsponding authors. MS with SCOUT-MTP Ion Source (Bruker Daltonics, Bremen) equipped with a nitrogen laser (337 nm), a gridless ion source, and reflector design. Size exclusion chromatography (SEC) analysis was performed on a TDA 301 Viscotek instrument equipped with two GMH HR -M columns with TSK-gel. Measurements were carried out at 35°C using THF (1.0 mL min -1 ) as mobile phase. A calibration method was created using narrow linear polystyrene standards. Corrections for the flow rate fluctuations were made using toluene as an internal standard.

J. Org. Chem. 2017, 82, 9751−