- Divergent synthesis of carbosilane wedges as dendritic building blocks: A new strategy towards core functionalised carbosilane dendrimers
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A divergent route for the synthesis of carbosilane wedges containing either a bromine or amine as a focal point has been developed for the construction of core functionalised dendrimers; carbosilane dendrimers up to the third generation containing a 1,3,5-benzene triamide core capable of binding guest molecules via hydrogen bonding have been prepared.
- Van Heerbeek, Rieko,Reek, Joost N.H.,Kamer, Paul C.J.,Van Leeuwen, Piet W.N.M.
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- Synthesis of carbosilane dendritic wedges and their use for the construction of dendritic receptors
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A divergent route for the synthesis of carbosilane wedges that contain either a bromine or amine as focal point has been developed. These new building blocks enable the construction of various core-functionalized carbosilane dendrimers. As a typical example carbosilane dendrimers up to the third generation containing a N,N′,N″-1,3,5-benzenetricarboxamide core (G1-G3) have been synthesized. This new class of molecules has been studied as host molecules and they have been found to bind protected amino acids as guest molecules via hydrogen bonding interactions. A decrease in the association constants was observed for the higher generation dendritic hosts, which is attributed to the increased steric hindrance around the core where the binding site is located. The binding properties of the dendritic host molecules can be tuned by modifying the binding motif at the core of the carbosilane dendrimers. A higher association constant for N-CBZ-protected glutamic acid 1-methyl ester (5) was observed when the third generation N,N′,N″-1,3,5-tris(l- alaninyl)benzenetricarboxamide core-functionalized carbosilane dendrimer (G3′) was used as the host molecule compared to G3. Different association constants for the formation of the diastereomeric G3′·l-5 (K = 295 M-1) and G3′·d-5 (K = 236 M-1) host-guest complexes were observed, pointing to a small enantioselective recognition effect. The difference between the association constants for the formation of the G3′·(l-5)2 and G3′·(d-5)2 host-guest complexes was much more pronounced, K = 37 M-1 versus K = 10 M-1, respectively. The Royal Society of Chemistry 2006.
- Van Heerbeek, Rieko,Kamer, Paul C. J.,Van Leeuwen, Piet N.M.W.,Reek, Joost N.H.
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- Packing for use in resolution
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The packing for use in resolution proposed for the liquid chromatography for particularly the opti-cal resolution of racemic compounds is prepared by reacting a silica gel carrier with a so-called silane treating agent to introduce a spacer part therein and chemically bonding it with a copper salt of a carboxylic or thiocarboxylic acid selected from the group consisting of optically active D- and L-2--acetizinecaroxylic acid, proline, hydroxyproline and allohydroxyproline. The steric bulkiness, the distance between the silica gel and the optically active group and the degree of hydrophobicity are specified so as to obtain an excellent resolving power.
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- SILAETHENE I. DARSTELLUNG UND CHARAKTERISIERUNG VON MONOSILACYCLOBUTANEN
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Monosilacyclobutanes of the type RR' are prepared by ring closure reactions of 3-halopropylhalosilanes and by substitution of SiCl containing silacyclobutane rings with organometallic reagents (RMgX, LiR, NaCp).Under optimal experimental conditions yields between 50 and 95percent can be obtained by both procedures.Characterization of the compounds is accomplished by analytical (C, H, N) and NMR, IR and mass spectroscopic investigations.
- Auner, N.,Grobe, J.
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