Regioselective O‑Sulfonylation of N,N‑Bis(2-hydroxyalkyl)tosylamides as a Synthetic Key Step to Enantiopure Morpholines

The synthesis of enantiopure 2,6-disubstituted morpholines was realized through sequential ring opening of two different optically pure oxiranes by a tosylamide, under solid–liquid phase-transfer catalysis (SL-PTC) conditions, mono-O-sulfonylation of the resulting tosylamido-2,2′-diol, and cyclizati...

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Bibliographic Details
Published in:Organic letters 2017-01, Vol.19 (1), p.70-73
Main Authors: Foschi, Francesca, Albanese, Domenico, Pecnikaj, Ilir, Tagliabue, Aaron, Penso, Michele
Format: Article
Language:English
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Summary:The synthesis of enantiopure 2,6-disubstituted morpholines was realized through sequential ring opening of two different optically pure oxiranes by a tosylamide, under solid–liquid phase-transfer catalysis (SL-PTC) conditions, mono-O-sulfonylation of the resulting tosylamido-2,2′-diol, and cyclization to the morpholine. The crucial step, the regioselective formation of the monosulfonate, was controlled by taking advantage of the different stereo, electronic, and coordination properties of the oxirane-derived side chains in the diol backbone. As an application of this protocol, a new morpholine-3-carboxamide was synthesized starting from threonine.
ISSN:1523-7060
1523-7052
DOI:10.1021/acs.orglett.6b03342