Kainz, Quirin M. and Zeltner, Martin and Rossier, Michael and Stark, Wendelin J. and Reiser, Oliver (2013) Synthesis of Trisubstituted Ureas by a Multistep Sequence Utilizing Recyclable Magnetic Reagents and Scavengers. CHEMISTRY-A EUROPEAN JOURNAL, 19 (30). pp. 10038-10045. ISSN 0947-6539,
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Unprecedented magnetic borohydride exchange (mBER), magnetic Wang aldehyde (mWang) and magnetic amine resins were prepared from highly magnetic polymer-coated cobalt or iron nanoparticles. Microwave irradiation was used to obtain excellent degrees of functionalization (>95%) and loadings (up to 3.0mmolg(-1)) in short reaction times of 15min or less. A small library of ureas and thioureas was synthesized by the exclusive application of these magnetic resins. As a first step, a reductive amination of aromatic and aliphatic aldehydes was carried out with mBER. The excess of primary amine needed to complete the reaction was subsequently scavenged selectively by mWang. Simple magnetic decantation from the resins resulted in secondary amines in good to excellent yields and purities. The used magnetic resins were efficiently regenerated and reused for the next run. In a second step, the secondary amines were converted to trisubstituted (thio)ureas in excellent yields and purities by stirring with an excess of iso(thio)cyanate, which was scavenged by addition of the magnetic amine resin after completion of the reaction. The whole reaction sequence is carried out without any purification apart from magnetic decantation; moreover, conventional magnetic stirring can be used as opposed to the vortexing required for polystyrene resins.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | SOLID-SUPPORTED REAGENTS; PHASE ORGANIC-SYNTHESIS; COMBINATORIAL CHEMISTRY; FUNCTIONALIZED POLYMERS; PALLADIUM CATALYST; AQUEOUS-SOLUTION; REDUCING AGENT; EXCHANGE RESIN; PRIMARY AMINES; NANOPARTICLES; amination; magnetic reagents; microwave chemistry; nanoparticles; synthetic methods |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie > Lehrstuhl Prof. Dr. Oliver Reiser |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 06 Apr 2020 08:22 |
| Last Modified: | 06 Apr 2020 08:22 |
| URI: | https://pred.uni-regensburg.de/id/eprint/16358 |
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