Improved Access to Chiral Tetranaphthoazepinium-Based Organocatalysts Using Aqueous Ammonia as Nitrogen Source
| Autor: | Michael Widhalm, Christina Schedl, Alexander Roller, Auraya Manaprasertsak, Sorachat Tharamak |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Bromides
Nitrogen Economic strategy Glycine Pharmaceutical Science organo catalysis Article Catalysis Analytical Chemistry lcsh:QD241-441 chemistry.chemical_compound Ammonia lcsh:Organic chemistry Drug Discovery chiral catalyst synthesis Physical and Theoretical Chemistry Organic Chemicals Nitrogen source Aqueous solution Molecular Structure Chemistry Aryl optical resolution Organic Chemistry Stereoisomerism Azepines 1 1′-binaphthyls Combinatorial chemistry Chemistry (miscellaneous) asymmetric phase transfer catalysis Molecular Medicine Common key |
| Zdroj: | Molecules Volume 24 Issue 21 Molecules, Vol 24, Iss 21, p 3844 (2019) |
| ISSN: | 1420-3049 |
| DOI: | 10.3390/molecules24213844 |
| Popis: | The class of 3,3&prime diaryl substituted tetranaphthobisazepinium bromides has found wide application as highly efficient C2-symmetrical phase-transfer catalysts (PTCs, Maruoka type catalysts). Unfortunately, the synthesis requires a large number of steps and hampers the build-up of catalyst libraries which are often desired for screening experiments. Here, we present a more economic strategy using dinaphthoazepine 7 as the common key intermediate. Only at this stage various aryl substituents are introduced, and only two individual steps are required to access target structures. This protocol was applied to synthesize ten tetranaphthobisazepinium compounds 1a&ndash 1j. Their efficiency as PTCs was tested in the asymmetric substitution of tert-butyl 2-((diphenylmethylene)amino)acetate. Enantioselectivities up to 92% have been observed with new catalysts. |
| Databáze: | OpenAIRE |
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