cas 24131-31-5, 3,5-Dibenzyloxybenzyl alcohol

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A Cd(ii) and Zn(ii) selective naphthyl based [2]rotaxane acts as an exclusive Zn(ii) sensor upon further functionalization with pyrene
A new multi-functional [2]rotaxane, ROTX, has been synthesized via a Cu(i) catalysed azide-alkyne cycloaddition reaction between Ni(ii) templated azide terminated pseudorotaxane composed of a naphthalene based heteroditopic wheel, NaphMC, and an alkyne terminated stopper. Subsequently, ROTX has been functionalized with pyrene moieties to develop a bifluorophoric [2]rotaxane, PYROTX, having naphthalene and pyrene moieties. Detailed characterization of these two rotaxanes is performed by utilizing several techniques such as ESI-MS, (1D and 2D) NMR, UV/Vis and PL studies. Comparative metal ion sensing studies of NaphMC (a fluorophoric cyclic receptor), ROTX ([2]rotaxane with a naphthyl fluorophore) and PYROTX ([2]rotaxane having naphthyl and pyrene fluorophores) have been performed to determine the effect of dimensionality/functionalization on the metal ion selectivity. Although NaphMC fails to discriminate between metal ions, ROTX serves as a selective sensor for Zn(ii) and Cd(ii). Importantly, PYROTX shows exclusive selectivity towards Zn(ii) over various transition, alkali and alkaline earth metal ions including Cd(ii).
Bej, Somnath,Nandi, Mandira,Ghosh, Pradyut
p. 294 - 303
(2021)
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Dendritic poly(benzyl ether)-b-poly(N-vinylcaprolactam) block copolymers: Self-organization in aqueous media, thermoresponsiveness and biocompatibility
Four generations of new amphiphilic thermoresponsive linear-dendritic block copolymers (LDBCs) with a linear poly(N-vinylcaprolactam) (PNVCL) block and a dendritic poly(benzyl ether) block are synthesized by atom transfer radical polymerization (ATRP) of N-vinylcaprolactam (NVCL) using dendritic poly(benzyl ether) chlorides as initiators. The copolymers have been characterized by 1H NMR, FTIR, and GPC showing controlled molecular weight and narrow molecular weight distribution (PDI ≤ 1.25). Their self-organization in aqueous media and thermoresponsive property are highly dependent on the generation of dendritic poly(benzyl ether) block. It is observed for the LDBCs that the self-assembled morphology changes from irregularly spherical micelles, vesicles, rod-like large compound vesicles (LCVs), to the coexistence of spherical micelles and rod-like LCVs, as the generation of the dendritic poly(benzyl ether) increases. The results of a cytotoxicity study using an MTT assay method with L929 cells show that the LDBCs are biocompatible.
Tang, Gang,Hu, Minqi,He, Fuxi,You, Dan,Qian, Yangyang,Bi, Yunmei
p. 300 - 308
(2018)
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Electrochemical Dimerization of Phenylpropenoids and the Surprising Antioxidant Activity of the Resultant Quinone Methide Dimers
A simple method for the dimerization of phenylpropenoid derivatives is reported. It leverages electrochemical oxidation of p-unsaturated phenols to access the dimeric materials in a biomimetic fashion. The mild nature of the transformation provides excellent functional group tolerance, resulting in a unified approach for the synthesis of a range of natural products and related analogues with excellent regiocontrol. The operational simplicity of the method allows for greater efficiency in the synthesis of complex natural products. Interestingly, the quinone methide dimer intermediates are potent radical-trapping antioxidants; more so than the phenols from which they are derived—or transformed to—despite the fact that they do not possess a labile H-atom for transfer to the peroxyl radicals that propagate autoxidation.
Romero, Kevin J.,Galliher, Matthew S.,Raycroft, Mark A. R.,Chauvin, Jean-Philippe R.,Bosque, Irene,Pratt, Derek A.,Stephenson, Corey R. J.
p. 17125 - 17129
(2018/12/04)

NOVEL FUNCTIONALIZED 1,3-BENZENE DIOLS AND THEIR METHOD OF USE FOR THE TREATMENT OF HEPATIC ENCEPHALOPTHY
Pharmaceutical compositions of the invention include novel functionalized 1,3-benzenediols having a disease-modifying action in the treatment of hepatic encephalopathy and related conditions. Pharmaceutical compositions of the invention further include novel neuroprotective agents.
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(2016/11/14)

Improved Catalytic Activity and Stability of a Palladium Pincer Complex by Incorporation into a Metal-Organic Framework
A porous metal-organic framework Zr6O4(OH)4(L-PdX)3 (1-X) has been constructed from Pd diphosphinite pincer complexes ([L-PdX]4- = [(2,6-(OPAr2)2C6H3)PdX]4-, Ar = p-C6H4CO2-, X = Cl, I). Reaction of 1-X with PhI(O2CCF3)2 facilitates I-/CF3CO2- ligand exchange to generate 1-TFA and I2 as a soluble byproduct. 1-TFA is an active and recyclable catalyst for transfer hydrogenation of benzaldehydes using formic acid as a hydrogen source. In contrast, the homogeneous analogue tBu(L-PdTFA) is an ineffective catalyst owing to decomposition under the catalytic conditions, highlighting the beneficial effects of immobilization.
Burgess, Samantha A.,Kassie, Abebu,Baranowski, Sarah A.,Fritzsching, Keith J.,Schmidt-Rohr, Klaus,Brown, Craig M.,Wade, Casey R.
supporting information
p. 1780 - 1783
(2016/03/01)

NOVEL FUNCTIONALIZED 1,3-BENZENE DIOLS AND THEIR METHOD OF USE FOR THE TREATMENT OF HEPATIC ENCEPHALOPATHY
Pharmaceutical compositions of the invention include novel functionalized 1,3-benzenediols having a disease-modifying action in the treatment of hepatic encephalopathy and related conditions. Pharmaceutical compositions of the invention further include novel neuroprotective agents.
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(2015/07/23)

Synthesis of Curvulone B Using the 2-Chlorobenzyl Protecting Group
A total synthesis of curvulone B has been completed using a Friedel-Crafts reaction and a highly cis-selective intramolecular oxa-Michael addition. The 2-chlorobenzyl protecting group was employed and found to have much greater Lewis acid stability compared to the simple benzyl group.
Bates, Roderick W.,Wang, Kongchen,Zhou, Guanying,Kang, Dave Zhihong
supporting information
p. 751 - 754
(2015/03/30)

Visual detection of fluoride ions
Dendrimer-hydrazides are coupled to polycyclic aromatic hydrocarbons for use in the visual detection of the presence of low levels of fluoride in a sample. The dendrimers can have a phenyl core, a first generation of aralkyl ethers, and an optional second generation of aralkyl ethers. The compounds form gels with solvents. In the presence of fluoride ion, the gels undergo color changes and/or gel to liquid phase change.
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(2015/12/18)

Effect of the bulkiness of the end functional amide groups on the optical, gelation, and morphological properties of oligo(p-phenylenevinylene) π-gelators
Herein, we describe the role of end functional groups in the self-assembly of amide-functionalized oligo(p-phenylenevinylene) (OPV) gelators with different end-groups. The interplay between hydrogen-bonding and π-stacking interactions was controlled by the bulkiness of the end functional groups, thereby resulting in aggregates of different types, which led to the gelation of a wide range of solvents. The variable-temperature UV/Vis absorption and fluorescence spectroscopic features of gelators with small end-groups revealed the formation of 1D H-type aggregates in CHCl3. However, under fast cooling in toluene, 1D H-type aggregates were formed, whereas slow cooling resulted in 2D H-type aggregates. OPV amide with bulky dendritic end-group formed hydrogen-bonded random aggregates in toluene and a morphology transition from vesicles into fibrous aggregates was observed in THF. Interestingly, the presence of bulky end-group enhanced fluorescence in the xerogel state and aggregation in polar solvents. The difference between the aggregation properties of OPV amides with small and bulky end-groups allowed the preparation of self-assembled structures with distinct morphological and optical features. Buying in bulk: OPV amides with small end-groups self-assemble into 2D/1D aggregates in toluene and 1D aggregates in CHCl3. Bulky end-groups impede fluorescence quenching in the self-assembled state by blocking π-stacking and facilitate morphological transition in THF.
Babu, Sukumaran Santhosh,Praveen, Vakayil K.,Kartha, Kalathil K.,Mahesh, Sankarapillai,Ajayaghosh, Ayyappanpillai
supporting information
p. 1830 - 1840
(2014/07/08)

A detailed investigation of light-harvesting efficiency of blue color emitting divergent iridium dendrimers with peripheral phenylcarbazole units
The increase in phosphorescence efficiency was estimated by the energy transfer mechanism for divergent iridium dendrimers with peripheral phenylcarbazole units. A series of Ir-core/phenylcarbazole-end dendrons of the type, Ir(dfppy)2(pic-Czsu
Cho, Yang-Jin,Wee, Kyung-Ryang,Son, Ho-Jin,Cho, Dae Won,Kang, Sang Ook
p. 4510 - 4521
(2014/03/21)

Biomimetic synthesis of active isorhapontigenin dimers
Synthetic isorhapontigenin was treated with several kinds of inorganic reagents and peroxidase so as to prepare active stilbene dimers. Among them, silver acetate in methanol gave two new isorhapontigenin dimers 4 and 5, together with four known natural stilbene dimers 2, 3, 6, and 7. Their structures and relative configurations were determined on the basis of spectral analysis, and their possible formation mechanisms were discussed, respectively. Compounds 2, 6, and 7 were artificially synthesized for the first time. All the products were evaluated for anti-inflammatory activities.
Wang, Xian-Fen,Zhang, Yuan,Lin, Ming-Bao,Hou, Qi,Yao, Chun-Suo,Shi, Jian-Gong
p. 511 - 521
(2014/06/09)

Polycationic ligands in gold catalysis: Synthesis and applications of extremely π-acidic catalysts
Very often ligands are anionic or neutral species. Cationic ones are rare, and, when used, the positively charged groups are normally appended to the periphery of the ligand. Here, we describe a dicationic phosphine with no spacer between the phosphorus atom and the two positively charged groups. This structural feature makes its donor ability poorer than that of phosphites and only comparable to extremely toxic or pyrophoric compounds such as PF 3 or P(CF3)3. By exploiting these properties, a new Au catalyst has been developed displaying a dramatically enhanced capacity to activate π-systems. This has been used to synthesize very sterically hindered and naturally occurring 4,5-disubstituted phenanthrenes. The present approach is expected to be applicable to the development and improvement of many other transition metal catalyzed transformations that benefit from extremely strong π-acceptor ligands. The mechanism of selected catalytic transformations has been explored by density functional calculations.
Carreras, Javier,Gopakumar, Gopinadhanpillai,Gu, Liangu,Gimeno, Ana,Linowski, Pawel,Petu?kova, Jekaterina,Thiel, Walter,Alcarazo, Manuel
supporting information
p. 18815 - 18823
(2014/01/06)

Supramolecular design for two-component hydrogels with intrinsic emission in the visible region
We report, for the first time, an in situ formation of two-component hydrogels from pyridine derivatives of poly(aryl ether) dendrons and tartaric acid. The two-component system (dendron + acid) undergoes J-type aggregation, leading to fibrillar type self-assembly in THF-water mixture along with blue (470 nm) and green (500 nm) intrinsic emissions. The Royal Society of Chemistry 2013.
Rajamalli,Atta, Supriya,Maity, Sandeepan,Prasad, Edamana
supporting information
p. 1744 - 1746
(2013/03/14)

Synthesis and antifungal properties of papulacandin derivatives
Derivatives of an antifungal agent that targets the β-(1,3)-D-glucan synthase, papulacandin D, were synthesized and tested for activity. The papulacandin D structure contains a challenging benzannulated spiroketal unit, which is introduced in a palladiumcatalyzed cross-coupling reaction of a glycal silanolate and an aryl iodide followed by an oxidative spiroketalization. Four different variants were made, differing in the nature of the acyl side chain with respect to the length, and in the number and stereochemistry of the double bonds. Moderate biological activity was observed for the derivatives with a side chain based on palmitic acid and linoleic acid.
Van Der Kaaden, Marjolein,Breukink, Eefjan,Pieters, Roland J.
supporting information; experimental part
p. 732 - 737
(2012/07/14)

Dendrimer solid acid and polymer electrolyte membrane including the same
Provided are a dendrimer solid acid and a polymer electrolyte membrane using the same. The polymer electrolyte membrane includes a macromolecule of a dendrimer solid acid having ionically conductive terminal groups at the surface thereof and a minimum amo
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Page/Page column 11-13

(2011/11/07)

Chemical synthesis and evaluation of 17α-alkylated derivatives of estradiol as inhibitors of steroid sulfatase
Steroid sulfatase (STS) controls the levels of 3-hydroxysteroids available from circulating steroid sulfates in several normal and malignant tissues. This and the known involvement of active estrogens and androgens in diseases such as breast and prostate cancers thus make STS an interesting therapeutic target. Here we describe the chemical synthesis and characterization of an extended series of 17α-derivatives of estradiol (E2) using different strategies. A variant of the samarium-Barbier reaction with stoichiometric samarium metal and catalytic Kagan reagent formation was used for introducing low reactive benzyl substrates in position 17 of estrone (E1) whereas heterocyclic substrates were metalated and reacted with either the carbonyl or the 17-oxirane of E1. In vitro evaluation of the inhibitory potency of the new compounds against STS identified new inhibitors and allowed a more complete structure-activity relationship study of this family of 17α-derivatives of E2.
Fournier, Diane,Poirier, Donald
experimental part
p. 4227 - 4237
(2011/11/12)

Low molecular weight fluorescent organogel for fluoride ion detection
The design, synthesis, and the photophysical properties of a Low Molecular Weight Gel (LMWG) based on AB3 and AB2 type poly(aryl ether) dendrons with an anthracene chromophore attached through an acylhydrazone linkage are described. The gel is utilized for an efficient 'naked eye' detection of fluoride ions (as low as 0.1 equiv with respect to the gelator concentration), through a reversible gel-sol transition, which is associated with a color change from deep yellow to bright red.
Rajamalli,Prasad, Edamana
supporting information; experimental part
p. 3714 - 3717
(2011/09/12)

Luminescent micro and nanogel formation from AB3 type poly(aryl ether) dendron derivatives without conventional multi-interactive gelation motifs
We report the synthesis, gelation and photophysical properties of luminescent AB3 type poly(aryl ether) dendron derivatives in the absence of conventional multi-interactive gelation motifs. The gelation process is controlled through employing partial polar solvent milieu, which significantly enhances the propensity of π-π interaction between the aryl units present in the system. The self-assembly leads to unprecedented gelation through entrapping solvent molecules in the fibrillar arrangement of poly(aryl ether) units. The strategy was further utilized to prepare an excimer based photoluminescent gel through incorporating anthracene units in the dendrons. The close proximity between the anthracene units in the gel renders the formation of anthracene excimers at room temperature, resulting in the emission of bright green light from the gel, upon UV excitation. The study suggests that the size and packing of the self-assembled fibre can be controlled by the generation and functional groups present in the dendron. Furthermore, the strategy envisages an easy approach to generate fluorescent Low Molecular-mass Organic Gelator (LMOG) through incorporating poly cyclic aromatic hydrocarbon units to the poly(aryl ether) dendrons, since the self-assembly is largely guided by π-π interactions. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Rajamalli,Prasad, Edamana
supporting information; experimental part
p. 1541 - 1548
(2011/09/20)

Synthesis of dendronized polymers through bergman cyclization of enediyne-containing Frechet-type dendrimers
In this article, dendronized polymers with rigid backbones were synthesized from enediyne-containing Frechet-type dendrimers. Two generations of dendrimers were conically incorporated with 3-(2-(2-(trimethylsilyl)ethynyl)phenyl)prop-2- yn-1-ol. The trimethylsilyl protection groups of enediyne units were subsequently removed, and two types of brush polymers with rigid conjugated backbone were prepared through Bergman cyclization polymerization at elevated temperature under vacuum. The dendronized polymers were characterized with GPC, IR, UV-vis, and NMR spectroscopy. Furthermore, the morphology of the dendronized polymer was revealed by atomic force microscopy.
Ma, Jianguo,Ma, Xiaowei,Deng, Sheng,Li, Fei,Hu, Aiguo
experimental part
p. 1368 - 1375
(2012/02/14)

Dimerization of piceatannol by Momordica charantia peroxidase and α-glucosidase inhibitory activity of the biotransformation products
Stilbenes, especially those oligomers, have great potential to be antihyperglycemic agents. In this study, eight stilbene dimers, including five new ones, were obtained by biotransformation of piceatannol using Momordica charantia peroxidase (MCP) for the first time. Their structures were established on the basis of spectroscopic evidences. These piceatannol dimers displayed potential α-glucosidase inhibitory activities, and trans double bond, tetrahydrofuran ring, and free adjacent phenolic dihydroxyls were found to be important for their activities. Enzymatic biotransformation of stilbenes by M. charantia peroxidase (MCP) was showed to be a prominent way to produce oligomeric stilbenes for antihyperglycemic development.
Wan, Xiang,Wang, Xiao-Bing,Yang, Ming-Hua,Wang, Jun-Song,Kong, Ling-Yi
experimental part
p. 5085 - 5092
(2011/10/08)

Total synthesis of (+)-papulacandin D
A total synthesis of (+)-papulacandin D has been achieved in 31 steps, in a 9.2% overall yield from commercially available materials. The synthetic strategy divided the molecule into two nearly equal sized subunits, the spirocyclic C-arylglycopyranoside and the polyunsaturated fatty acid side-chain. The C-arylglycopyranoside was prepared in 11 steps in a 30% overall yield from triacetoxyglucal. The fatty acid side-chain was also prepared in 11 steps in a 30% overall yield from geraniol. The key strategic transformations in the synthesis are: (1) a palladium-catalyzed, organosilanolate-based cross-coupling reaction of a dimethylglucal-silanol with an electron-rich and sterically hindered aromatic iodide and (2) a Lewis-base catalyzed, enantioselective allylation reaction of a dienal and allyltrichlorosilane. A critical element in the successful execution of the synthesis was the development of a suitable protecting group strategy that satisfied a number of stringent criteria.
Denmark, Scott E.,Kobayashi, Tetsuya,Regens, Christopher S.
supporting information; experimental part
p. 4745 - 4759
(2010/08/06)

Synthesis of organometallic poly(dendrimer)s by macromonomer polymerization: effect of dendrimer size and structural rigidity on the polymerization efficiency
Two series of first to third generation (G1-G3) oligoether dendrimers, one hearing a shorter spacer chain (C-O) and the other having a longer spacer branch (C-C-C-O) were prepared. Both series of compounds, containing two reactive C≡CH moieties on the dendrimer surface, were used as macromonomers and copolymerized with trans-[Pt(PEt3)2Cl2] to form organometallic poly(dendrimer)s by an outer-sphere-outer-sphere connection strategy. It was found that concentration of monomer used in the polymerization, the dendrimer generation, and, most strikingly, the length of the spacer were key factors that determined the polymerization efficiency. Hence, the structurally more rigid and compact C-O linked dendrimers formed poly(dendrimer)s with a higher degree of polymerization than the structurally less rigid and more bulky C-C-C-O dendrimers. This result was due to the higher tendency to form cyclic oligomers in the latter series of compounds. In addition, the differences in the polymerization efficiency among the three generations of dendrimers could be explained by the gradual decrease of reactive functional group density on the dendrimer surface.
Cheung, Siu-Yin,Chow, Hak-Fun,Ngai, To,Wei, Xiaoling
supporting information; experimental part
p. 2278 - 2288
(2009/10/23)

Stabilization of G-quadruplex DNA with platinum(II) Schiff base complexes: Luminescent probe and down-regulation of c-myc oncogene expression
The interactions of a series of platinum(II) Schiff base complexes with c-myc G-quadruplex DNA were studied. Complex [PtL1a] (1a; H 2L1a= N,N'-bis(salicylidene)-4,5-methoxy-1,2- phenylenediamine) can moderately inhibit c-m
Wu, Peng,Ma, Dik-Lung,Leung, Chung-Hang,Yan, Siu-Cheong,Zhu, Nianyong,Abagyan,Che, Chi-Ming
experimental part
p. 13008 - 13021
(2010/06/16)

Efficient total synthesis of piceatannol via (e)-selective wittig-horner reaction
Efficient and practical total synthesis of piceatannol via (E)-selective Wittig-Horner reaction is demonstrated with six steps in overall 40% yield from a commercially available, cheap starting material, 3,5-dihydroxybenzoic acid. Wittig-Horner reaction o
Young Han, Su,Suck Lee, Hyun,Hye Choi, Da,Woon Hwang, Jung,Mo Yang, Deok,Jun, Jong-Gab
experimental part
p. 1425 - 1432
(2009/09/30)

Dendritic chiral phosphine lewis bases-catalyzed asymmetric aza-Morita-Baylis-Hillman reaction of N-sulfonated imines with activated olefins
A series of polyether dendritic chiral phosphine Lewis bases was synthesized, and successfully applied to the asymmetric aza-Morita - Baylis - Hill -man reaction of N - sulfonated imines (N - arylmethyl -idene-4- methylbenzenesulfonamides) with methyl vin
Liu, Ying-Hao,Shi, Min
supporting information; experimental part
p. 122 - 128
(2009/04/10)

Triazole-linked dendro[60]fullerenes: modular synthesis via a 'click' reaction and acidity-dependent self-assembly on the surface
A series of Fréchet-type dendron functionalized [60]fullerene derivatives that bear a 1,2,3-triazole linkage group, referred to as triazole-linked dendro[60]fullerenes, were prepared via a modular synthetic protocol based on a Cu-catalyzed [3+2] cycloaddi
Mahmud, Ilias M.,Zhou, Ningzhang,Wang, Li,Zhao, Yuming
experimental part
p. 11420 - 11432
(2009/04/11)

Synthesis of dendritic phenol ether derivatives with a naphthalene core
A series of dendritic phenol ether derivatives with a naphthalene core were synthesized by the Williamson reaction as a coupling reaction between 1-hydroxymethylnaphthalene and polyether-based dendritic fragments in the presence of phase-transfer catalyst and alkali. The modified method for chlorination of dendritic benzyl alcohol was also developed using PPh3 and CCl4 as reagents and CH2Cl2/CCl4 as solvent. Copyright Taylor & Francis Group, LLC.
Xiang, Zhonghua,Cao, Derong
p. 1318 - 1324
(2008/09/19)

Catalysis by titanocene-functionalized polymer-supported dendrimers
A series of variously-functionalized first-, second-, and third-generation dendrimers have been prepared and linked via a biphenyl core to a bis-styryl moiety suitable for use as a crosslinker in polymerization. Attachment of titanocene moieties to the first-generation system and copolymerization with styrene affords polymeric disks that exhibit catalytic properties superior to comparable solution-phase systems in a multicomponent coupling of chlorosilanes with Grignards to give bis-allylic silanes.
Berget, Patrick E.,Teixeira, Jacqueline M.,Jacobsen, John L.,Schore, Neil E.
p. 8101 - 8103
(2008/03/13)

Hydrogen-bonded dendronized polymers and their self-assembly in solution
Frechet-type benzyl ether dendrons of second and third generations with a carboxyl group (G2, G3) at the apex site could attach to poly(4-vinylpyridine) (PVP), forming hydrogen-bonded dendronized polymers (HB denpols) in their common solvent, chloroform. The HB denpols show unique self-assembly behavior, forming vesicles in the common solvent under ultrasonic treatment. The structure and morphology of the vesicles were characterized by dynamic light scattering (DLS), static light scattering (SLS), SEM, TEM, and AFM. The size of the vesicles decreases and the thickness of the vascular membrane increases as the molar ratio of Gx/PVP increases. The hydrogen bonding. π-π aromatic stacking of the dendrons. and the considerable difference in architecture between the dendron Gx and PVP are the main factors facilitating the assembly of the HB denpols in the common solvent.
Xie, Dang,Jiang, Ming,Zhang, Guangzhao,Chen, Daoyong
p. 3346 - 3353
(2008/02/08)

Total synthesis of papulacandin D
A total synthesis of the antifungal agent papulacandin D is reported. The molecule is representative of a large class of C-aryl glycosides that exhibit significant antifungal activity. The synthetic strategy bifurcates the molecule into two nearly equal subunits, the arylglycoside and 18-carbon fatty acid side chain. The key strategic transformations are (1) the palladium catalyzed, organosilanolate-based cross-coupling of a protected glucal silanol and (2) a catalytic enantioselective allylation of a dienal using allyltrichlorosilane. The synthesis was accomplished in 31 steps overall from commercial starting materials to afford over 50 mg of the natural product. Copyright
Denmark, Scott E.,Regens, Christopher S.,Kobayashi, Tetsuya
p. 2774 - 2776
(2008/02/02)

Optical switching and antenna effect of dendrimers with an anthracene core
Dendrimers 6Gi (i=1-4) consisting of an anthracene core and Frechet dendrons which are attached via a CH2OCH2 chain in the 9-position undergo quantitative and completely reversible intramolecular [4π+4π] cycloaddition. The
Cao, Derong,Dobis, Silvia,Gao, Chunmei,Hillmann, Sabine,Meier, Herbert
p. 9317 - 9323
(2008/12/20)

Dendrimer analogues of linear molecules to evaluate energy and charge-transfer properties
We have designed and synthesized difunctionalized dendrimers containing two donors in the periphery and an acceptor at the core to serve as scaffolds for comparison with linear analogues to investigate the advantage of dendritic scaffolds for energy and c
Nantalaksakul, Arpornrat,Dasari, Raghunath Reddy,Ahn, Tai-Sang,Al-Kaysi, Rabih,Bardeen, Christopher J.,Thayumanavan
p. 2981 - 2984
(2007/10/03)

Total synthesis of (±)-quadrangularin A
The key to successful coupling in the synthesis of (±)- quadrangularin A (1) was the introduction of tert-butyl groups in the precursor to block two reactive positions. Thus, the oxidative coupling of 3,5-di-(tert-butyl) resveratrol was carried out regioselectively in an efficient total synthesis of the natural product. (Chemical Equation Presented)
Li, Wenling,Li, Hao,Li, Ying,Hou, Zijie
p. 7609 - 7611
(2008/02/12)

Synthesis and retrostructural analysis of libraries of AB3 and constitutional isomeric AB2 phenylpropyl ether-based supramolecular dendrimers
We report the synthesis of methyl esters of 3-(4-hydroxyphenyl)propionic, 3-(3,4-dihydroxyphenyl)propionic, 3-(3,5-dihydroxyphenyl)propionic, and 3-(3,4,5-trihydroxyphenyl)propionic acids and their use in a convergent iterative strategy to prepare up to four generations of three libraries, one of 3,4,5- and two of constitutional isomeric 3,4- and 3,5-substituted 3-phenylpropyl dendrons. Each library contains 3-[3,4,5-tris(dodecyl-1-oxy) phenyl]propyl-, 3-[3,4-bis(dodecyl-1-oxy)phenyl]propyl-, 3-{3,4-bis[3-(4- dodecyl-1-oxyphenyl)propyl-1-oxy]phenyl}propyl-, and 3-{3,4,5-tris[3-(4-dodecyl- 1-oxyphenyl)propyl-1-oxy]phenyl}propyl ether first-generation dendrons on their periphery and -CO2CH3, -COOH, and -CH2OH groups at their apex. Regardless of their generation number and their periphery, internal, and apex structures, these dendrons self-assemble into supramolecular dendrimers that self-organize into all periodic and quasi-periodic assemblies encountered previously and in several unencountered with architecturally related benzyl ether-based supramolecular dendrimers. A variety of porous columnar lattices that were previously obtained only from dendritic dipeptides and hollow supramolecular spheres were also discovered from these building blocks. The more flexible and less compact 3-phenylpropyl ether repeat units are stable under acidic conditions, facilitate a simpler synthetic strategy, provide faster dynamics of self-assembly into higher-order supramolecular structures of larger dimensions, exhibit lower transition temperatures than the corresponding benzyl ether homologues, and demonstrate the generality of the self-assembly concept based on amphiphilic dendrons.
Percec, Virgil,Peterca, Mihai,Sienkowska, Monika J.,Ilies, Marc A.,Aqad, Emad,Smidrkal, Jan,Heiney, Paul A.
p. 3324 - 3334
(2007/10/03)

Facile synthesis of aryl ether dendrimer from unprotected AB2 building blocks using thionyl chloride as an activating agent
A novel, rapid, inexpensive, and highly efficient convergent approach for the synthesis of a Frechet- type aryl ether dendrimer using thionyl chloride has been developed. In this method, the purification of each dendron and a dendrimer occurs by recrystallization, extraction, and precipitation. The MALDI-TOF MS spectrum supported the formation of the G2, G3, and G4 dendrons and the star-shaped G4 dendrimer.
Yamazaki, Natsuko,Washio, Isao,Shibasaki, Yuji,Ueda, Mitsuru
p. 2321 - 2324
(2007/10/03)

The first total synthesis of SB87-Cl and pestalone, novel bioactive benzophenone natural products
SB87-Cl 1, an inhibitor of testosterone-5α-reductase, and pestalone 2 exhibiting effective antimicrobial activity against MRSA (MIC=37ng/mL) and VRE (MIC=78ng/mL), were novel bioactive benzophenone natural products. Total synthesis of 1 and 2 has been successfully accomplished. The common synthetic precursor 18 of 1 and 2, was successfully obtained by the coupling of 8 with 12.
Iijima, Daisuke,Tanaka, Daisuke,Hamada, Motoko,Ogamino, Takahisa,Ishikawa, Yuichi,Nishiyama, Shigeru
p. 5469 - 5471
(2007/10/03)

Preparation and structural characterisation of terpy-cored dendrimers and dendriplexes
2,2′:6′,2″-Terpyridine (terpy) ligands and their iron(n) and cobalt(n) complexes bearing first and second generation Frechet-type dendritic wedges have been prepared and structurally characterised. The rotational freedom within the dendritic wedge results
Constable, Edwin C.,Housecroft, Catherine E.,Neuburger, Markus,Schaffner, Silvia,Scherer, Lukas J.
p. 2635 - 2642
(2007/10/03)

Synthesis of a piceatannol analog: Replacement of hydroxy group with amide functionality
Polyhydroxylated stilbene analogs of piceatannol are shown to possess protein-tyrosine kinase (PTK) inbibitory activity. We have developed a novel approach to introduce an amide moiety into the structure of piceatannol. The amido substituted stilbene deri
Venkatachalam,Huang,Yu,Uckun
p. 1489 - 1497
(2007/10/03)

Synthesis of versatile intermediates of the ferrocene series: Reductive amination of ferrocenecarbaldehyde
Reductive amination of ferrocenecarbaldehyde with several primary and secondary amines in the presence of sodium triacetoxyborohydride was studied. This method was used for the synthesis of new ferrocenylmethylamines, viz., N-(ferrocenylmethyl)isoleucine methyl ester, N,N-bis(ferrocenylmethyl)glycine ethyl ester, and N-(3,5-dibenzyloxybenzyl)-N-(ferrocenylmethyl)methylamine. The latter is a potential precursor of a dendrimer with the chiral ferrocenyl plane in the core.
Khrushcheva,Sokolov
p. 830 - 833
(2007/10/03)

Dendronized protein polymers: Synthesis and self-assembly of monodisperse cylindrical macromolecules
Monodisperse dendronized protein polymers (DPPs), cylindrical dendrimers containing protein core, can be efficiently produced through a combined modular biosynthetic strategy. These DPP materials possess predictable size, shape, and solubility. In organic
Zhuravel, Michael A.,Davis, Nicolynn E.,Nguyen, SonBinh T.,Koltover, Ilya
p. 9882 - 9883
(2007/10/03)

Synthesis of resveratrol using a direct decarbonylative Heck approach from resorcylic acid
The phytoalexin resveratrol has been made using a decarbonylative Heck reaction. The acid chloride derived from 3,5-dihydroxybenzoic acid was coupled with 4-acetoxystyrene in the presence of palladium acetate and N,N-bis-(2,6-diisopropylphenyl)dihydroimidazolium chloride to give the substituted stilbene in 73% yield as the key step.
Andrus, Merritt B.,Liu, Jing,Meredith, Erik L.,Nartey, Edward
p. 4819 - 4822
(2007/10/03)

Synthesis of difunctionalized dendrimers: An approach to main-chain poly(dendrimers)
Synthesis of benzyl ether dendrimers that are difunctionalized at their peripheries are described. These dendrimers should form the basis for a new class of main-chain dendritic polymers. The steric protection afforded at higher generation during the synt
Ganesh, Renuka N.,Shraberg, Joshua,Sheridan, Patrick G.,Thayumanavan
p. 7217 - 7220
(2007/10/03)

Photoisomerization of stilbene dendrimers: The need for a volume-conserving isomerization mechanism
Highly branched stilbene dendrimers were synthesized and their photochemical behavior was studied. Even the stilbene dendrimer with molecular weight over 6500 underwent transcis isomerization in the excited singlet state within the lifetime of 10 ns. The
Uda, Mayuko,Mizutani, Takuo,Hayakawa, Junpei,Momotake, Atsuya,Ikegami, Masashi,Nagahata, Ritsuko,Arai, Tatsuo
p. 596 - 605
(2007/10/03)

A new convergent approach to dendritic macromolecules
The novel convergent growth approach to dendritic macromolecules is described. Polyether dendritic sectors [G-na]-OH from the first to the fourth generations, respectively, were prepared by this approach from readily available starting material.
Cao, Xiaoping,Wang, Feng,Guo, Shu
p. 3149 - 3158
(2007/10/03)

Mechanistic studies on the biomimetic reduction of tetrahydroxynaphthalene, a key intermediate in melanin biosynthesis
1,3,6,8-Tetrahydroxynaphthalene (T4HN) is an aromatic polyketide, serving as a general precursor of fungal melanin. Melanin biosynthesis involves two consecutive deoxygenations of T4HN, consisting of the reduction of a phenolic carbon followed by dehydrat
Ichinose,Ebizuka,Sankawa
p. 192 - 196
(2007/10/03)

A simple method for controlling dendritic architecture and diversity: A parallel monomer combination approach
A novel parallel monomer combination approach to manipulating the architectural disposition of dendritic macromolecules is described. It harnesses the synthetic speed and power of the double-stage convergent growth approach and classical parallel synthesi
Freeman,Chrisstoffels,Frechet
p. 7612 - 7617
(2007/10/03)

Arylamide inhibitors of HIV-1 integrase
Based on data derived from a large number of HIV-1 integrase inhibitors, similar structural features can be observed, which consist of two aryl units separated by a central linker. For many inhibitors fitting this pattern, at least one aryl ring also requires orth obis-hydroxylation for significant inhibitory potency. The ability of such catechol species to undergo in situ oxidation to reactive quinones presents one potential limitation to their utility. In an effort to address this problem, a series of inhibitors were prepared which did not contain ortho bishydroxyls. None of these analogues exhibited significant inhibition. Therefore an alternate approach was taken, whose aim was to increase potency rather than eliminate catechol substructures. In this latter study, naphthyl nuclei were utilized as aryl components, since a previous report had indicated that fused bicyclic rings may afford higher affinity relative to monocyclic phenyl-based systems. In preliminary work with monomeric units, it was found that the 6,7-dihydroxy- 2-naphthoic acid (17) (IC50 = 4.7 μM) was approximately 10-fold more potent than its 5,6-dihydroxy isomer 19 (IC50 = 62.4 μM). Of particular note was the dramatic difference in potency between free acid 17 and its methyl ester 21 (IC50 > 200 μM). The nearly total loss of activity induced by esterification strongly indicates that the free carboxylic -OH is important for high potency of this compound. This contrasts with the isomeric 5,6-dihydroxy species 19, where esterification had no effect on inhibitory potency (23, IC50 = 52.7 μM). These data provide evidence that the monomeric 6,7- and 5,6-dihydroxynaphthalenes may be interacting with the enzyme in markedly different fashions. However, when these naphthyl nuclei were incorporated into dimeric structures, significant enhancements in potencies each relative to the monomeric acids were observed, with bis-6,7- dihydroxy analogue 49 and bis-5,6-dihydroxy analogue 51 both exhibiting approximately equal potencies (IC50 values of 0.81 and 0.11 μM, respectively).
Zhao, He,Neamati, Nouri,Mazumder, Abhijit,Sunder, Sanjay,Pommier, Yves,Burke Jr., Terrence R.
p. 1186 - 1194
(2007/10/03)

Asymmetric Synthesis of a Series of Chiral AB2 Monomers for Dendrimer Construction
Efficient preparation of a series of four chiral, nonracemic AB2 monomers suitable for the construction of dendrimers is presented. Monomers 1-4 possess the common structural features of a diphenolic moiety and a benzylic or aliphatic hydroxyl which render these molecules suitable for convergent dendrimer synthesis. The same basic, high-yielding, five-step sequence is employed for 1-4. Stilbene derivatives 13 and 14 are prepared by a Horner-Wadsworth-Emmons modified Wittig reaction between 3,5- or 3,4-bis(benzyloxy)benzaldehyde (8 and 10) and an ester-substituted benzylphosphonate (11 or 12). Cinnamate derivatives 21 and 22 are prepared similarly from 8 and 10 and triethyl phosphonoacetate. Chirality is introduced in the form of a 1,2-diol unit by Sharpless asymmetric dihydroxylation (AD) (>97% ee in all cases). Protection of the 1,2-diols as their acetonide derivatives provides dioxolane intermediates 17, 18, 25, and 26. Reduction of the ester groups followed by hydrogenolysis of the benzyl ethers yields AB2 monomers 1-4 in 57-67% overall yield from 8 and 10.
McElhanon, James R.,Wu, Mu-Jen,Escobar, Maya,Chaudhry, Umer,Hu, Chun-Ling,McGrath, Dominic V.
p. 908 - 915
(2007/10/03)

Induction of liquid crystallinity by host-guest interactions
A molecular clip is described which binds aromatic guests by an induced fit mechanism. It contains twelve long aliphatic chains and can evoke liquid-crystalline properties in a variety of molecules, including polymers and porphyrins, by a process of molecular recognition.
Van Nunen, Johanna L. M.,Folmer, Brigitte F. B.,Nolte, Roeland J. M.
p. 283 - 291
(2007/10/03)

Synthesis of Chiral Starburst Dendrimers from PHB-Derived Triols as Central Cores
Chiral triols 1-3 ('tris(hydroxymethyl)methane' derivatives), prepared from (R)-3-hydroxybutanoic acid and aldehydes, are used as center pieces of dendrimers.The triols may be employed as such or after attachment of spacers containing alkyl or aryl moieti
Seebach, Dieter,Lapierre, Jean-Marc,Greiveldinger, Guy,Skobridis, Konstantinos
p. 1673 - 1688
(2007/10/02)