کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5220788 | 1383399 | 2011 | 9 صفحه PDF | دانلود رایگان |
With the aim of improving catalytic performance and recyclability various ionic-liquid-tagged organocatalysts (ILTOCs) based on (S)-proline as organocatalysts and triazolium or guanidinium salts as ionic liquid tags were applied in the asymmetric α-aminoxylation of ketones and aldehydes with nitrosobenzene in IL as solvents. Amongst such ILTOC’s compounds were found which performed better (ee >99%, yield 97%) than (S)-proline in reported cases. Recycling and reusage of ILTOCs were easily possible and yields higher than 80% and ees higher than 90% were obtained until the fifth cycle. Important information about the crucial role of water in recycling of proline-derived organocatalysts in reactions with carbonyl compounds via enamine activation was found to prevent blockade of the organocatalyst by oxazolidinone formation.
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Journal: Tetrahedron - Volume 67, Issue 10, 11 March 2011, Pages 1812–1820