CuCl-catalyzed cleavage of S-triphenylmethyl thioether: a new detritylation method for thio group

A new method for the deprotection of trityl thioethers using CuCl as the catalyst under ultrasonic conditions is described.     

A General Method for the Rapid High Yield Preparation of Pure Arsonium Salts. Preparation Of (3-Alkoxy-Carbonyl-2-Oxopropyl)Triphenylarsonium Bromides

An easy, rapid method for the preparation of arsonium salts of high yield and purity, by heating an alkyl halide and triphenylarsine as a melt at about 80°C, is described.     

RGD-conjugated triarylmethyl radical as probe for electron paramagnetic imaging

A stable RGD-conjugated triarylmethyl (TAM) radical 3 has been synthesized in a straightforward three-step sequence. CT-03 ‘the Finland trityl’ which is a very popular contrast agent for electron paramagnetic resonance imaging has been covalently bound to the NH₂-ending of a pentapeptide commonly used to target integrins and confers tissue selectivity. Moreover, this new TAM radical is stable and sensitive to molecular oxygen.     

Application of Ball Milling Technology to Carbohydrate Reactions: I. Regioselective Primary Hydroxyl Protection of Hexosides and Nucleoside by Planetary Ball Milling‡

Dry ball milling of hexosides with trityl chloride in the presence of DABCO or Na₂CO₃ has been found to result in their complete conversion to the respective 6‐O‐trityl ethers. Further wet grinding of the reaction mixture with Ac₂O in the presence of DMAP led to the respective fully protected hexosides in good to excellent yields after isolation. It has been found to be an effective one‐pot two‐step synthesis under solvent‐free condition. The speed of homogenization has been shown to highly influence the rate and outcome of the reaction, and commercially available planetary ball mill has been proved to be very convenient for carrying out the reaction under standardized and reproducible conditions.     

C−F Transformations of Benzotrifluorides by the Activation of Ortho-Hydrosilyl Group

Single C−F transformations of aromatic trifluoromethyl compounds are challenging issues due to the strong C−F bond. We have recently developed selective methods for single C−F transformations such as allylation of o-hydrosilyl-substituted benzotrifluorides through the hydride abstraction with trityl cations. Single C−F thiolation and azidation of o-(hydrosilyl)benzotrifluorides were achieved using trityl sulfides and trityl azide catalyzed by Yb(OTf)₃. Treatment of o-(hydrosilyl)benzotrifluorides with trityl chloride resulted in single C−F chlorination. The resulting fluorosilyl group served in further transformations including protonation, halogenation, and Hiyama cross-coupling with C−Si cleavage. We also synthesized benzyl fluorides by LiAlH₄-reduction of the resulting fluorosilanes and further C−F transformations. These methods enabled us to prepare a broad range of organofluorines from simple benzotrifluorides through C−F and C−Si transformations.     

Cationic ring-opening polymerization of carbazolyl-containing epoxy monomers by triphenyl carbenium salts as thermal- and photolatent initiators

Abstract  Photoinitiated cationic polymerizations of various epoxy monomers bearing a carbazole moiety, 9-[3-(allyloxy)-2-(oxiran-2-ylmethoxy)propyl]-9H-carbazole, 9-[3-methoxy-2-(oxiran-2-ylmethoxy)propyl]-9H-carbazole, 9-[2-(oxiran-2-ylmethoxy)ethyl]-9H-carbazole, as well as a composition of 3,6-dibromo-9-(oxiran-2-ylmethyl)-9H-carbazole with 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate were investigated in bulk using triphenyl carbenium salts having anions such as BF₄ ⁻, SnCl₅ ⁻, and SbCl₆ ⁻. Dark polymerizations of the carbazolyl monomers in the presence of the initiators are studied. These photoinduced polymerization reactions give oligomers of degree of polymerization 4-22. The effect of the anion of the photoinitiator and polymerization time on the polymerization reaction is discussed. Graphical abstract        

A Facile Synthesis and Crystallographic Analysis of Seven Trityl Phosphorus Compounds and Two Nickel(II) Phosphine Side-Products

Abstract  The syntheses and X-ray analyses of triphenylmethyl (trityl=Tr) phosphorus compounds are reported and the structural similarities, differences and ³¹P chemical shifts compared. A series of seven trityl-substituted phosphorus-containing compounds have been characterized by single crystal X-ray diffraction. Ph₃CPPh₂, 1, a bulky P(III) compound crystallizes in the triclinic space group , a = 7.5624(6) ?, b = 9.5470(8) ?, c = 16.9722(14) ?, α = 83.4720(10)°, β = 80.541(2)°, γ = 68.1580(10)°, the borane complex of 1, 2, Ph₃CPPh₂(BH₃) crystallizes as monoclinic colorless crystals, P2₁/c, a = 10.0972(12) ?, b = 9.6955(12) ?, c = 25.197(3) ?, β = 90.258(2)°. The analogous methyl substituted, 3, Ph₃CPMe₂(BH₃) is monoclinic, C₂/c, a = 15.628(3) ?, b = 12.770(3) ?, c = 18.406(4) ?, β = 103.968(3)°. Compounds 4–7 are trityl substituted P(V) compounds: Ph₃CP(Ph)(O)(OH), 4, crystallizes in the triclinic space group , a = 8.9847(18) ?, b = 9.7443(19) ?, c = 12.786(3) ?, α = 72.045(3)°, β = 72.031(3)°, γ = 78.769(3)°. Esterification of 4 affords TrCP(O)(Ph)OBn 5, space group, P2₁/c, a = 7.9196(5) ?, b = 31.701(2) ?, c = 19.8062(13) ?, β = 99.7750(10)°. A phosphonate diester was also characterized, Ph₃CP(O)(OEt)₂, 6, triclinic, , a = 7.9521(17) ?, b = 9.2205(19) ?, c = 14.471(3) ?, α = 85.906(4)°, β = 83.031(4)°, γ = 68.283(4)°. Treatment of the trityl H-phosphinic acid, Ph₃CPO₂H_2, with elemental selenium yields yellow crystals of 7, [Ph₃CP(O)(OH)Se]_2, P2₁/c, a = 9.0603(4) ?, b = 22.3652(11) ?, c = 16.9134(7) ?, β = 107.035(2)°. In our efforts to isolate a nickel-phosphine complex, two Ni(II) complexes were crystallographically analyzed, [Ni(OP(H)Ph₂)₆]₂BF₄ ⁻ 8 and 9. Complex 8 with an uncoordinated BF₄ ⁻ ion crystallizes as yellow orthorhombic crystals, Pbca, a = 18.8247(12) ?, b = 18.5518(12) ?, c = 21.0976(14) ?, while crystals of 9 are trigonal, , a = b = 13.1545(12) ?, c = 68.461(9) ?. Graphical Abstract  The syntheses and X-ray analyses of triphenylmethyl (trityl=Tr) phosphorus compounds are reported and the structural similarities, differences and ³¹P chemical shifts compared.      

A new combination of protecting groups and links for encoded synthetic libraries suited for consecutive tests on the solid phase and in solution

Summary A strategy for high-throughput evaluation of combinatorial compound libraries is reported, which circumvents the necessity to test complex mixtures. The method is based on a new combination of protecting groups, solid-phase linker and tags. The bulk of the library first undergoes a binding assay with the components grafted on beads. A selection of beads carrying strong ligands is stripped from the labelled target and distributed into microvessels. The ligands are cleaved and rinsed into microeluates. Subsequently, a more detailed characterization with a functional assay in solution determines the best performers, which are identified through the peptidic tag left behind on the corresponding mother bead.Abbreviations Boc tert-butyloxycarbonyl - CCL combinatorial compound libraries - Ddz ,-dimethyl-3,5-dimethoxybenzyloxycarbonyl - DICD N,N-diisopropylcarbodiimide - DIPEA diisopropylethylamine - DMA dimethylacetamide - ESL encoded synthetic libraries - FITC fluoresceinisothiocyanate - GABA -aminobutyric acid - HOBT N-hydroxybenzotriazole - MALDI matrix-assisted laser desorption ionization - Pbf 2,2,4,6,7-pentamethyldihydrobenzofuran-5-sulfonyl - Pmc 2,2,5,7,8-pentamethylchroman-6-sulfonyl - TFA trifluoroacetic acid - Trt trityl     

Convenient multigram synthesis of monodisperse oligo(ethylene glycols): effective reaction monitoring by infrared spectroscopy using an attenuated total reflection fibre optic probe

A convenient approach for the synthesis of monodisperse oligo(ethylene glycols) up to 12 units is described. A novel cleavage protocol replacing laborious hydrogenolysis is introduced to achieve a fast, inexpensive and widely applicable procedure. In addition to the synthetic part, Fourier transform infrared (FTIR) spectroscopy using a fibre optic attenuated total reflection (ATR) sensor was applied to monitor the formation of sensitive key intermediates, resulting in optimized reaction times. By applying this in-line technique, the possibility of real-time analysis under inert conditions was impressively demonstrated.     

An improved and general synthesis of monomers for incorporating trityl linker groups into polystyrene synthesis supports

A straightforward synthesis of trityl alcohols in which one of the aryl rings is substituted with a vinyl group is presented. The synthesis of the alcohols involves the direct addition of the Grignard reagent prepared from 4-bromostyrene to substituted benzophenones. These compounds are used to incorporate trityl linker groups into polystyrene-based organic synthesis supports. Both non-cross-linked and cross-linked (JandaJel™) polystyrene have been prepared using these monomers.