Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts
This work presents the synthesis of six new phase-transfer organocatalysts in which the squaramide unit is directly linked to the nitrogen atom of an aza-crown ether. Four chiral skeletons, namely hydroquinine, quinine, cinchonine (cinchonas), and α-<span style="font-variant: small-caps;&quo...
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MDPI AG
2021
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oai:doaj.org-article:3043392d84704e3ab447a2447677f4722021-11-11T18:31:41ZSynthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts10.3390/molecules262165421420-3049https://doaj.org/article/3043392d84704e3ab447a2447677f4722021-10-01T00:00:00Zhttps://www.mdpi.com/1420-3049/26/21/6542https://doaj.org/toc/1420-3049This work presents the synthesis of six new phase-transfer organocatalysts in which the squaramide unit is directly linked to the nitrogen atom of an aza-crown ether. Four chiral skeletons, namely hydroquinine, quinine, cinchonine (cinchonas), and α-<span style="font-variant: small-caps;">d</span>-glucopyranoside were responsible for the asymmetric construction of an all-carbon quaternary stereogenic center in α-alkylation and Michael addition reactions of malonic esters. We investigated the effects of these different chiral units and that of crown ethers with different sizes on catalytic activity and enantioselectivity. During extensive parameter investigations, both conventional and emerging green solvents were screened, providing valuable α,α-disubstituted malonic ester derivatives with excellent yields (up to 98%).Zsuzsanna FehérDóra RichterSándor NagyPéter BagiZsolt RapiAndrás SimonLászló DrahosPéter HuszthyPéter BakóJózsef KupaiMDPI AGarticleasymmetric catalysisphase-transfer catalysisenantioselectivityallylationcrown compoundscarbohydratesOrganic chemistryQD241-441ENMolecules, Vol 26, Iss 6542, p 6542 (2021) |
| institution |
DOAJ |
| collection |
DOAJ |
| language |
EN |
| topic |
asymmetric catalysis phase-transfer catalysis enantioselectivity allylation crown compounds carbohydrates Organic chemistry QD241-441 |
| spellingShingle |
asymmetric catalysis phase-transfer catalysis enantioselectivity allylation crown compounds carbohydrates Organic chemistry QD241-441 Zsuzsanna Fehér Dóra Richter Sándor Nagy Péter Bagi Zsolt Rapi András Simon László Drahos Péter Huszthy Péter Bakó József Kupai Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts |
| description |
This work presents the synthesis of six new phase-transfer organocatalysts in which the squaramide unit is directly linked to the nitrogen atom of an aza-crown ether. Four chiral skeletons, namely hydroquinine, quinine, cinchonine (cinchonas), and α-<span style="font-variant: small-caps;">d</span>-glucopyranoside were responsible for the asymmetric construction of an all-carbon quaternary stereogenic center in α-alkylation and Michael addition reactions of malonic esters. We investigated the effects of these different chiral units and that of crown ethers with different sizes on catalytic activity and enantioselectivity. During extensive parameter investigations, both conventional and emerging green solvents were screened, providing valuable α,α-disubstituted malonic ester derivatives with excellent yields (up to 98%). |
| format |
article |
| author |
Zsuzsanna Fehér Dóra Richter Sándor Nagy Péter Bagi Zsolt Rapi András Simon László Drahos Péter Huszthy Péter Bakó József Kupai |
| author_facet |
Zsuzsanna Fehér Dóra Richter Sándor Nagy Péter Bagi Zsolt Rapi András Simon László Drahos Péter Huszthy Péter Bakó József Kupai |
| author_sort |
Zsuzsanna Fehér |
| title |
Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts |
| title_short |
Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts |
| title_full |
Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts |
| title_fullStr |
Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts |
| title_full_unstemmed |
Synthesis of Novel Crown Ether-Squaramides and Their Application as Phase-Transfer Catalysts |
| title_sort |
synthesis of novel crown ether-squaramides and their application as phase-transfer catalysts |
| publisher |
MDPI AG |
| publishDate |
2021 |
| url |
https://doaj.org/article/3043392d84704e3ab447a2447677f472 |
| work_keys_str_mv |
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