- Highly efficient synthesis of monodisperse poly(ethylene glycols) and derivatives through macrocyclization of oligo(ethylene glycols)
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A macrocyclic sulfate (MCS)-based approach to monodisperse poly(ethylene glycols) (M-PEGs) and their monofunctionalized derivatives has been developed. Macrocyclization of oligo(ethylene glycols) (OEGs) provides MCS (up to a 62-membered macrocycle) as versatile precursors for a range of monofunctionalized M-PEGs. Through iterative nucleophilic ring-opening reactions of MCS without performing group protection and activation, a series of M-PEGs, including the unprecedented 64-mer (2850Da), can be readily prepared. Synthetic simplicity coupled with versatility of this new strategy may pave the way for broader applications of M-PEGs. Macrocycles make synthesis easier: Convenient macrocyclization of the OEGs provides versatile macrocyclic sulfates. These compounds are cornerstones for both monofunctionalization of OEGs and highly efficient synthesis of monodisperse PEGs and derivatives, including an unprecedented 64-mer.
- Zhang, Hua,Li, Xuefei,Shi, Qiuyan,Li, Yu,Xia, Guiquan,Chen, Long,Yang, Zhigang,Jiang, Zhong-Xing
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p. 3763 - 3767
(2015/03/18)
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- Synthesis of oligo(ethylene glycol) toward 44-mer
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A synthetic method for oligo(ethylene glycol) toward 44-mer (FW = 1956.35) is described. Reiteration of Williamson's ether synthesis and hydrogenation to remove protecting benzyl group affords desired oligo(ethylene glycol) toward 44-mer in moderate yields. The advantages in this method are use of commercially easily available materials as starting materials and procedures avoiding difficulty in purification of the products as much as possible.
- Ahmed, Saleh A.,Tanaka, Mutsuo
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p. 9884 - 9886
(2007/10/03)
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- Multigram Synthesis of Well-Defined Extended Bifunctional Polyethylene Glycol (PEG) Chains
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A series of novel, well-defined, unsymmetrical poly(ethylene glycol) chains of the type X(OCH2-CH2)nY (where X = protecting group; Y = nucleofuge or a different protecting group; n = 3, 6, 9, 12, 15, 18, and 24) were prepared in high yields by applying orthogonal protecting groups. The purity of the compounds was fully verified by elemental and high-resolution mass spectrometry analyses.
- Loiseau, Francois A.,Hii, King Kuok,Hill, Alison M.
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p. 639 - 647
(2007/10/03)
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- An expedient synthesis of monodispersed oligo(ethylene glycols)
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A convenient approach to the synthesis of oligo(ethylene glycols) under phase transfer conditions is described. Oligo(ethylene glycols) (x = 7-12) are obtained in excellent yields and high purity via modular, bi-directional elongation of readily available ethylene glycol bis-tosylates.
- Burkett, Brendan A.,Chan, Tak Hang
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p. 1007 - 1010
(2007/10/03)
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- Synthesis and analysis of polyethylene glycol linked P-glycoprotein-specific homodimers based on (-)-stipiamide
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A series of five homodimeric polyethylene glycol (PEG) linked homodimers based on the multidrug resistance reversal agent (-)-stipiamide were made and tested for their ability to interact with P-glycoprotein, the protein responsible for multidrug resistance, using ATPase and photoaffinity displacement assays. Key reactions include a new alkoxide-mesylate displacement for the assembly of the PEG linkers and a double Sonogashira coupling reaction.
- Andrus, Merritt B.,Turner, Timothy M.,Updegraff, Emily P.,Sauna, Zuben E.,Ambudkar, Suresh V.
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p. 3819 - 3822
(2007/10/03)
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- Preparation and crystallinity of a large unsubstituted crown ether, cyclic heptacosa(oxyethylene) (cyclo-E27, 81-crown-27), studied by Raman spectroscopy, X-ray scattering and differential scanning calorimetry
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Cyclic heptacosa(oxyethyelene) (cyclo-E27, 81-crown-27) was prepared from linear α-hydro, ω-hydroxy-heptacosa(oxyethylene) by reaction with tosyl chloride under alkaline conditions, purified by preparative-scale gel permeation chromatography, and studied by laser-Raman spectroscopy, wide-angle and small-angle X-ray scattering, and differential scanning calorimetry. Comparison was made with the properties of linear oligo(oxyethylene) dimethyl ethers (including C1E27C1). The sub-cell of the crystalline cyclic oligomer was the same as that of its linear counterparts, i.e. the same as that of high-molar-mass poly(oxyethylene). However, the cyclic oligomer crystallised as a twice-folded ring, as confirmed by its long spacing and the frequency of its single-node longitudinal acoustic mode (LAM-1). Enthalpies of fusion and melting temperatures were analysed to provide estimates of the enthalpy and entropy of formation of a fold in an oligo(oxyethylene) layer crystal.
- Yang, Zhuo,Yu, Ga-Er,Cooke, Jennifer,Ali-Adib, Ziad,Viras, Kyriakos,Matsuura, Hiroatsu,Ryan, Anthony J.,Booth, Colin
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p. 3173 - 3182
(2007/10/03)
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- TEMPLATE EFFECTS. 7. LARGE UNSUBSTITUTED CROWN ETHERS FROM POLYETHYLENE GLYCOLS: FORMATION, ANALYSIS, AND PURIFICATION
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Through the reaction of polyethylene glycols with tosyl chloride and heterogeneous KOH in dioxane not only coronands from crown-4 to crown-8 can be obtained but also larger homologues.A systematic investigation has shown that: i) crown-9 and crown-10 can be formed from nona- and deca-ethylene glycol, respectively, and isolated in pure form; ii) the whole series of polyethylene glycols from tri- to deca-ethylene glycol yields not only the corresponding crown ethers but also higher cyclooligomers that can be analyzed up to about crown-20 by glc: in particular crown-12 and crown-16 were obtained from tetraethylene glycol and purified by column chromatography on cellulose; iii) the reaction, as applied to commercial mixtures of polyethylene glycols (from PEG 200 to PEG 1000), gives fairly high yields of crown ethers also in the region of large ring sizes.The contribution of the template effect of K(+) ion and the cyclooligomerization reactions for the various ring sizes are discussed.
- Vitali, Chiara Antonini,Masci, Bernardo
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p. 2201 - 2212
(2007/10/02)
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- Intramolecular End-to-End Reactions of Photoactive Terminal Groups Linked by Poly(oxyethylene) Chains
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The triplet-sensitized photochemical reaction using a series of poly(oxyethylene) chains with a pair of photoactive terminal groups, dibenzazepine (DBA) chromophores (DBA-COCH2CH2(OCH2CH2)nOCH2CH2CO-DBA, n=0-10) was examined.The photoirradiation of bichromophoric compounds caused either intra- or intermolecular reactions.These reactions were kinetically analyzed by two different methods: the measurement of deactivation processes of the reaction intermediates (excited triplet state of DBA) by nanosecond laser photolysis and the quantitative analysis of the reaction products by GPC.The intramolecular deactivation rate constant, kintra, showed a remarkable chain-length dependence; the maximum kintra value appeared at n=5 and it was found to be 5.9X104 s-1.On the other hand, the intramolecular cyclization rate also depends on the chain length; the maximum quantum yield, φintrad, was given at n=7 (φintrad=0.51).The chain length for the maximum cyclization yield shifted slightly to the longer region than that for the maximum kintra value due to the restriction of the terminal structure (anti-configuration).The results obtained for this reaction system are compared with those obtained for the previously reported polymethylene system and the effect of chain flexibility on the intramolecular ring-closure reaction is discussed.
- Ashikaga, Kazuo,Ito, Shinzaburo,Yamamoto, Masahide,Nishijima, Yasunori
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p. 2443 - 2450
(2007/10/02)
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- A NOVEL, UNEQUIVOCAL SYNTHESIS OF POLYETHYLENE GLYCOLS
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Unequivocal synthesis of polyethyleneglycols is presented.The key step for this synthesis is the selective monobenzylation of oligoethyleneglycols by the phase transfer catalysis technique.
- Coudert, Gerard,Mpassi, Michel,Guillaumet, Gerald,Selve, Claude
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- Ring-Closure Reactions. 19. Kinetics of Formation of Benzo-Crown Ethers by Intramolecular Nucleophilic Substitution. A Comparison between Poly(oxyethylene) and Polymethylene Chains
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Kinetic data have been obtained for the formation of 9-, 12-, 15-, 21-, 30-, and 48-membered benzo-crown ethers by intramolecular Williamson synthesis in Me2SO-water (99:1, v/v).Comparison with earlier data for the formation of catechol polymethylene ethers provides an insight into the influence on the ease of ring closure of the replacement of methylene groups by oxygen atoms.Little or no effect occurs at ring size 9.In the next higher homologues the ease of cyclization of the poly(oxyethylene) chains is some 3 times as great as that of the polymethylene chains of similar length, but in the limit of the very long chains the two series behave much in the same way.Interestingly, literature data related to the fast, encounter-controlled reactions between end groups linked by poly(oxyethylene) and polymethylene chains reveal much the same features of the slow, activation-controlled reactions.The general picture fits in with well-established conformational arguments based on the expected strain relief due to replacement of trasannular CH...HC interactions with CH...O or O...O interactions.The oxygen atom effect turns out to be a sensitive tool for the detection of even weak strain energies in ring compounds.
- Illuminati, Gabriello,Mandolini, Luigi,Masci, Bernardo
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p. 4142 - 4145
(2007/10/02)
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- Detergent compounds and compositions
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Compounds of the formula STR1 wherein R1 and R2 are each straight chain, branched chain or cyclic alkyl, alkenyl, aryl, aralkyl or alkaryl moieties having from 1-30 carbon atoms; R3 is a C2 -C8 alkylene, alkenylene, arylene or alkarylene moiety; R4 is a C1 -C8 alkylene, alkenylene, arylene or alkarylene moiety; A is a water-solubilizing anionic moiety; and n is from 1 to about 100 are useful as surfactants. Compounds wherein groups R1, R2 and R3 and integer n are selectively chosen provide good clay soil detergency performance even in the absence of builders. The compounds are usefully combined with other organic surfactants to provide detergent compositions having good clay and oily soil removal performance.
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