B ernd H enkel, Lianshan Zhang, Carsten G oldam m er, Ernst Bayer* Institute of Organic Chemistry, University of Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen, Germany Z. Naturforsch. 51b, 1339-1346 (1996); received April 10, 1996 HIV 1-Protease, Trityl-Linker, Fragment Condensation, Peptide Synthesis, Ionspray-MS, Chiral Gas-chromatography A new trityl-linker for the strategy of combined...

This article reports the development and evaluation of two nano-emulsions (F45T-03/HFB and F15T-03/PFOB) containing fluorinated trityl radicals dissolved in perfluorocarbons. Preparation with a high-pressure homogenizer conferred sub-micronic size to both nano-emulsions. In vitro and in vivo EPR spectroscopy showed that the nano-emulsions had much greater oxygen sensitivity than the hydrophilic...

Beta-hydroxy amides 6 and 7 were treated with triphenylphosphonium anhydride trifluoromethane sulfonate (3), or the cyclic analogue 4, to generate 2-oxazolines 5 and 8 under mild conditions. The reaction was optimised by examining the number of equivalents of reagents 3 or 4, or diisopropylethyl amine required to best effect cyclisation. The effects of altering the reaction temperature, reactio...

Carbazole-based materials adopting the nonconjugated substitution of triphenylsilyl (-SiPh(3)) and trityl (-CPh(3)) side groups are studied as high-triplet-energy, morphologically, and electrochemically stable host materials with tunable carrier-transport properties for organic blue electrophosphorescence. The developed host materials 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole ...

The modified triester approach has been further improved and refined to the synthesis of defined sequences of deoxyribo-oligonucleotides. Improvements include arylsulfonyltetrazoles as faster and milder condensing agents, benzenesulfonic acid to avoid depurination during deblocking of trityl protecting groups and improved chromatographic procedures for purification of triester intermediates and...

Dimesitylphosphinoisoprene 9a reacts with a series of R-B(C6F5)2 boron Lewis acids by isomerization and subsequent 1,4-P/B addition to give the heterocyclic phosphonium/borate zwitterionic products 13. Subsequent hydride abstraction from the isoprenyl derived methyl group by trityl cation proceeds with elimination of the R-B(C6F5)2 reagent to give the heterocyclic phosphonium system 20.

For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ω(0)(-2) field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partial...

Abbreviations used: Acm, acetamidomethyl; Boc, tert-butoxycarbonyl; Bzl, benzyl; Bzl(4-Me), 4-methylbenzyl; DPDS, di(2-pyridyl)disulfide; DMSO, dimethylsulfoxide; Fmoc, 9-fluorenylmethoxycarbonyl; Mob, 4-methoxybenzyl; Npys, 3-nitro-2-pyridylsulfanyl; Pys, 2-pyridylsulfanyl; StBu, tert-butylsulfanyl; sec, selenocysteine; tBu, tert-butyl; TFA, trifluoroacetic acid; TfOH, trifluoromethanesulfonic...

Contrary to other studies, here we describe cysteine (Cys) pseudoproline-containing peptides with short deprotection times in TFA. The deprotection times fell in the same range as other protecting groups commonly used in SPPS (e.g., 1-3 h). Moreover, when using Cys pseudoprolines as peptide macrocyclization-enhancing moieties a considerable reduction in reaction time was observed compared to a ...