نتایج جستجو برای: polymer supported halogenations
تعداد نتایج: 285825 فیلتر نتایج به سال:
Recent developments concerning the application of polymer supported organometallic reagents in solid phase synthesis are reviewed, with a special focus on methodology for carbon-carbon formation. Examples of reactions that are covered include the classical Suzuki, Sonogashira and Heck coupings, but also aryl amination, epoxide opening, rearrangements, metathesis and cyclopropanation. Applicatio...
The polymer supported phosphazene bases PS-P₂(tBu) and the novel PS-P₂(PEG) allowed for efficient extraction of [¹⁸F]F⁻ from proton irradiated [¹⁸O]H₂O and subsequent radiofluorination of a broad range of substrates directly on the resin. The highest radiochemical yields were obtained with aliphatic sulfonates (69%) and bromides (42%); the total radiosynthesis time was 35-45 min. The multivaria...
[reaction: see text] p-Methoxybenzyl ethers have been found to transfer from alcohols to sulfonamides in the presence of catalytic trifluoromethanesulfonic acid. This process for protecting group removal can be performed in solution with yields >94%. Through the use of sulfonamide-functionalized ("safety-catch") resins, p-methoxybenzyl ethers can be cleaved in excellent yields with minimal puri...
A new polymer supported synthesis of deoxyribooligonucleotides which can be adapted to automation is described. The method is based on the elongation of an oligomer chain in the 5'- to 3' -end direction using the modified phosphotriester chemistry. The approach is exemplified by the synthesis of a nonanucleotide d(TTCGTCTTG).
High chemical yields and good enantiomeric excesses are obtained by using soluble polymer-supported tartrate ester in the epoxidation of trans-hex-2-en-1-ol using Ti(OPri)4/tert-butyl hydroperoxide.
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