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Substitution Products (substitution + products)
Selected AbstractsTripodands with Phenyl and Thiophenyl Rings and Nitrogen Bridgehead Atoms,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2006Martin Baier Abstract The flexible tripodands 7,9 and 15 with phenyl and thiophenyl rings as "legs" and nitrogen as bridgehead atoms have been synthesized by three-component condensation reactions of the corresponding amine with the aryl halide. The more rigid species 10,14 and 17 were built up from the podands 7,9 as well as from their iodine substitution products 33,35 by a sequence of ethynylation and C,C coupling reactions. Podand 16 was prepared from tris-iodide 36 by Sonogashira coupling with phenylacetylene. In the cases of 7, 12, 15,17, 22, 24, 35, 36, and 41 the structural parameters were determined by X-ray studies. With the exception of 7, 12, and 17, all structures show either close intermolecular contacts between heteroatoms (15, 22, 24, 35, and 36), C,H···N hydrogen bonding (41), or are closely packed as a result of ,···, stacking (16). We were able to isolate silver triflate complexes of 9, 10, and 16, and in the case of 9 we obtained crystals suitable for X-ray diffraction studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Reactions of Chlorosulfanyl Derivatives of Cyclobutanones with Different NucleophilesHELVETICA CHIMICA ACTA, Issue 5 2006Agnieszka Majchrzak Abstract The reactions of 3-chloro-3-(chlorosulfanyl)-2,2,4,4-tetramethylcyclobutan-1-one (2) with N, O, S, and P nucleophiles occur by substitution of Cl at the S-atom. Whereas, in the cases of secondary amines, alkanols, phenols, thiols, thiophenols, and di- and trialkyl phosphates, the initially formed substitution products were obtained, the corresponding products with allyl and propargyl alcohols undergo a [2,3]-sigmatropic rearrangement to give allyl and allenyl sulfoxides, respectively. Analogous substitution reactions were observed when 3-chloro-3-(chlorodisulfanyl)-2,2,4,4-tetramethylcyclobutan-1-one (3) was treated with N, O, and S nucleophiles. The reaction of 3 with Et3P led to an unexpected product via cleavage of the SS bond (cf. Scheme,13). In the reactions of 2 with primary amines and H2O, the substitution products react further via elimination of HCl to yield the corresponding thiocarbonyl S -imides and the thiocarbonyl S -oxide, respectively. Whereas the latter could be isolated, the former were not stable but could be intercepted by MeOH (Scheme,4) or adamantanethione (Scheme,5). The structures of some of the substitution products were established by X-ray crystallography. [source] Gold(III) Chloride-Catalyzed Diastereoselective Alkylation Reactions with Chiral Benzylic AcetatesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2008Philipp Rubenbauer Abstract Gold(III) chloride was shown to be an efficient catalyst for the diastereoselective CC bond formation of various chiral para -methoxybenzylic acetates and different nucleophiles. All electrophilic acetates carried next to the reacting center a stereogenic carbon center bound to a functional group (FG), a methyl substituent and a proton. Selectivities were good (dr>80/20) in favor of the anti -product for FG=COOMe, NO2, CN and in favor of the syn -product for FG=SO2Et, PO(OEt)2. The reactions proceed most likely via a free carbocation, in which a face differentation is facilitated by a preferred conformation. Several arene nucleophiles were shown to be compatible with the catalysis conditions providing the corresponding substitution products in high yields (13 examples, 62,98%). Moreover, other nucleophiles (allyltrimethylsilane, trimethylsilyl cyanide, 2,2-dimethyl-3-(trimethylsilyloxy)butane, p -toluenesulfonamide, and acetylacetone) reacted with a representative chiral electrophile in a high yielding and diastereoselective fashion. [source] Systematic MALDI-TOF CID Investigation on Different Substituted mPEG 2000MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 6 2010Katrin Knop Abstract Methoxy poly(ethylene glycol) 2000 (mPEG 2000) samples were substituted via esterification reactions to convert the hydroxyl end group of the mPEG into potential initiators for the cationic ring opening polymerization of 2-oxazolines. These substitution products were investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS); in addition, detailed MALDI-TOF/TOF-collision induced dissociation (CID) MS studies were performed to introduce this method as complementary structural characterization tool allowing the detailed analysis of the prepared macromolecules. The CID of the macroinitiators revealed 1,4-hydrogen and 1,4-ethylene eliminations forming very regular fragmentation patterns which showed, depending on the end groups, different fragmentation series. Furthermore, very pronounced McLafferty,+,1 rearrangements (1,5 hydrogen-transfer) of the introduced ester end groups were observed leaving the mPEG molecule as neutral acid. This incisive loss revealed the exact molar mass for each end group and, therefore, represents an important tool for end group determination of functionalized polymers. [source] | ||||||||||