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Hydrophobic Chitosan Derivatives for Liposome Modification O.O

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Hydrophobic Chitosan Derivatives for Liposome Modification O.O Hydrophobic chitosan derivatives for liposome modification O.O. Koloskova, U.A. Budanova, Yu.L. Sebyakin Moscow/Russia Moscow state university of fine chemical technology named after M.V. Lomonosov, prospekt Vernadskogo 86, 119571, Moscow [email protected] Chitosan is an abundant natural polysaccharide with huge availability and potential for biomedical applications due to its biocompatibility, biodegradability, and bioactivity, but its utilization in pharmaceutical formulations has been greatly limited by its intractability. Owing to its semicrystalline nature and multiple H-bond forming groups, chitosan is insoluble in water (when pH > 6.2) and all common organic solvents. Therefore, many works are dedicated to synthesis of new chitosan derivatives to improve its properties for the applications. For example, chitosan is an attractive polymer for liposome modification to obtain a steric stabilized particles. In this work we synthesized a chitosan derivative with residue of palmitic acid as a hydrophobic anchor (which will penetrate into liposomal bilayer and fixate chitosan on the surface). The reaction was carried out in the presence of EDC in the mixture of acetonitrile and a low-concentration solution of acetic acid. The product was purified by washing with non-polar solvents. The structure of the target compound was confirmed by 1H- NMR spectroscopy. As a result, the derivative of chitosan have been synthesized and it can be used to create a steric barrier on the surface of liposomes. This work was supported by the Russian Foundation for Basic Research (grant № 13- 04-00841). Photocatalysis with Visible Light – a Sustainable Application for the Falling Film Microreactor Rehm, T. H. Mainz/DE, Löb, P. Mainz/DE Fraunhofer ICT-IMM, Carl-Zeiss-Straße 18-20, 55129 Mainz, Germany. The utilization of visible light has become an important research field for the synthesis of fine chemicals. Several methods have been developed with pure organic or metal organic sensitizers for homogeneously photocatalysed reactions under mild reaction conditions being close to room temperature and pressure (Biological Process Win- dows).1 In conjunction with continuous-flow synthesis protocols microstructured reac- tors are increasingly applied as further sustainable key technology. For example, a fal- ling film microreactor (FFMR) enables the optimized control over the dimension of the liquid phase both on generating very thin liquid films for complete illumination and ex- cellent gas-liquid contacting.2 The synergistic approach to combine photocatalysis with visible light and microreactors for continuous-flow synthesis enables the access to a very young and promising field of synthetic organic chemistry.3 In a feasibility study the FFMR was combined with light sources of individual power and emission wavelength for performing photochemical con- versions with gas-liquid contacting. BMR1: photooxygenation of 1,5-dihydroxynaphthalene to Juglone;4 BMR2: photooxida- tion of p-methoxybenzyl alcohol to p-methoxybenzaldehyde.1e A commercially available cold-white LED lamp (14.2 W) and newly designed LED arrays adapted to the quartz glass win- dow of the FFMR were used for the irradiation of the reaction solution (green (3.4 W) for Rose Bengal; blue (2 W) for riboflavin tetraacetate or tetraphenylporphyrine). In case of BMR1 (#1) the photoreactor setup applied results in a strongly increased prod- uct yield, whereupon the green LED array is superior to the white light LED lamp re- garding the energy efficiency. In comparison to Entry 1 the use of TPP instead of RB gives lower yield, but increases once more the energy efficiency (#2). BMR2 (#3) was successfully transferred from batch to continuous-flow mode with equal yield. Here, the use of the blue LED array gives the best energy efficiency. Table 1: Reaction conditions and results for BMRs (tresidence ≈ 19 s, T = 20 °C, fliquid = 0.08 mL/min, fsynthetic air = 2 mL/min; ISP = 2-propanol). # Reaction Starting material Solvent Light emission of LED Type of LED Literature Sensitizer [mM] [mM] Yield [%] Efficiency [%·W-1·h-1] [%] 1 BMR1 1,5-Dihydroxy- ISP/water White Green White Green White Rose Bengal [0.5] Naphthalene [10] 9/1 92 71 1225 3944 10 (ref.4) 2 BMR1 1,5-Dihydroxy- 1,4- Blue Green Blue Green / Tetraphenylporphyrine [0.5] Naphthalene [10] Dioxane 49 <1 4642 <189 / 3 BMR2 p-Methoxy- ISP/water White Blue Green White Blue Green Blue Riboflavin tetraacetate [0.2] benzyl alcohol [2] 1/1 60 36 19 800 3411 1059 58 (ref.1e) The strongly increased yield in BMR1 and the transfer to continuous-flow mode for BMR2 give a first outlook on the potential of the falling film microreactor for photocata- lytic applications. Ongoing work focuses on the development of a reactor concept to be applied to various photochemical reactions in conjunction with the highly specific adap- tation of the photocatalyst and the light source on the chemical reaction. 1 a) D. Ravelli, D. Dondi, M. Fagnoni, A. Albini, Chem. Soc. Rev. 2009, 38, 1999-2011; b) J. Xuan, W.-J. Xiao, Angew. Chem. Int. Ed. 2012, 51, 6828-6838; c) S. Füldner, R. Mild, H. Siegmund, J. Schroeder, M. Gruber, B. König, Green Chem. 2010, 12, 400-406; d) M. Neumann, S. Füldner, B. König, K. Zeitler, Angew. Chem. Int. Ed. 2011, 50, 951-954; e) H. Schmaderer, P. Hilgers, R. Lechner, B. König, Adv. Synth. Catal. 2009, 351, 163-174; f) D. Hari, P. Schroll, B. König, J. Amer. Chem. Soc. 2012, 134, 2958-2961; g) S. Protti, M. Fagnoni, Photochem. Photobiol. Sci. 2009, 8, 1499-1516; h) C. Prier, D. Rankic, D. MacMillan, Chem. Rev., 2013, 113, 5322-5363. 2 V. Hessel, S. Hardt, H. Löwe, A. Müller, G. Kolb, Chemical Micro Process Engineering 2005, Wiley-VCH, Weinheim. 3 a) E. Coyle, M. Oelgemöller, Photochem. Photobiol. Sci. 2008, 7, 1313-1322; b) M. Oelgemöller, Chem. Eng. Technol. 2012, 35, 1144-1152; c) B. Mason, K. Price, J. Steinbacher, A. Bogdan, T. McQuade, Chem. Rev. 2007, 107, 2300-2318; d) H. Lu, M. Schmidt, K. Jensen, Lab Chip, 2001, 1, 22-28; e) R. Wootton, R. Fortt, A. de Mello, Org. Proc. Res. Devel. 2002, 6, 187-189; f) Y. Matsushita, N. Ohbab, S. Kumadab, K. Sakeda, T. Suzuki, T. Ichimura, Chem. Eng. J. 2008, 135S, S303-S308; g) R. Gorges, S. Meyer, G. Kreisel, J. Photochem. Photobiol. A: Chemistry 2004, 167, 95-99. 4 O. Shvydkiv, C. Limburg, K. Nolan, M. Oelgemöller, J. Flow Chem. 2012, 2, 52-55. Rh(III)-catalyzed Halogenations: Arenes, Alkenes and Heterocycles N. Schröder, Münster, J. Wencel-Delord, Münster, N. Kuhl, Münster, F. Lied, Münster, F. Glorius, Münster Nils Schröder, Organisch-Chemisches Institut, Westfälische Wilhems-Universität Münster, Corrensstraße 40, 48149 Münster, Germany The metal-catalyzed direct functionalization of C-H bonds has emerged over the last decade as a modern and environmentally friendly tool for organic synthesis. However, the applications of this strategy to create carbon-heteroatom bonds, and, in particular, carbon-halogen bonds, are still surprisingly limited. A general method enabling the high-yielding and selective formation of most valuable and versatile (with regard to further transformations) C-Br and C-I bonds, compatible with a large scope of diverse reactants, such as arenes, alkenes and hetereocycles, is of prime synthetic value. Herein, we report our efforts and recent advances in the Rh(III)-catalyzed bromination and iodination. The halogenation of arenes was achieved with excellent efficiency and [1] selectivity, as well as a broad scope in terms of different directing groups. DG DG [RhIIICp*] + NXS H X = Br, I X + ortho-C-H bromination and iodination + versatile (33 examples) + efficient (up to 99% yield) [2] The selective synthesis of Z-halo acrylamides was achieved using a similar protocol. ra id access to Z-halo acr lic amides p y + easily available via starting materials direct halogenation of vinylic C-H bonds + variable R DG R DG substitution patterns Rh(III) + Z-selective R H NXS R X X = Br, I + valuable building blocks In addition recent results on the selective halogenation of heterocycles are reported. Literature: [1] N. Schröder, J. Wencel-Delord, F. Glorius J. Am. Chem. Soc. 2012, 134, 8298- 8301. [2] N. Kuhl, N. Schröder, F. Glorius Org. Lett. 2013, 15, 3860-3863. Asymmetric Hydrogenation of Thiophenes and Benzothiophenes Catalyzed by a Ruthenium-NHC Complex Daniel Paul, Münster, Slawomir Urban, Münster, Bernhard Beiring, Münster, Nuria Ortega, Münster and Frank Glorius, Münster Daniel Paul, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, [email protected] Asymmetric hydrogenation of aromatic compounds is a straightforward method for the synthesis of chiral (hetero)cycles, which are important structural motives, especially in medicinal and biological chemistry. Several aromatics like quinolines, indoles or (benzo)furans have been hydrogenated in the past, showing excellent yields and enantioselectivities.[1] Difficulties remained in the hydrogenation of strong sigma-donating molecules like sulfur containing aromatics, which tend to poison the homogenous catalyst. Thiophenes and their (partly) reduced pendants are widely distributed in natural products. But the formation of diverse and enantiopure derivates remains challenging.[2] The homogenous hydrogenation of unsubstituted thiophene and benzothiophene has been extensively studied in order to understand the heterogenous hydrodesulfurization-reaction (HDS). Unfortunately, just one precedence is known for substituted thiophenes and none for substituted benzothiophenes[3] We will present an efficient and asymmetric ruthenium-N-heterocyclic carbene-catalyzed hydrogenation of substituted thiophenes and benzothiophenes, providing a new strategy for the formation of valuable enantiomerically pure tetrahydrothiophenes and 2,3- dihydrobenzothiophenes.[4] Literature: [1] Wang, D.-S.; Chen, Q. A.; Lu, S. M.; Zhou, Y.-G. Chem. Rev. 2012, 112, 2557. [2] Benetti, S.; De Risi, C.; Pollini, G. P.; Zanirato, V. Chem. Rev. 2012, 112, 2129. [3] Borowski, A. F.; Sabo-Etienne, S.; Donnadieu, B.; Chaudret, B. Organometallics 2003, 22, 4803. [4] Urban, S.; Beiring, B.; Ortega, N.; Paul, D.; Glorius, F., J.
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