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Diastereo- and Enantioselective Synthesis of N-Protected 2-Amino 1,4-Diols by an Oxa Michael Addition/1,3-Dipolar Cycloaddition Protocol

โœ Scribed by Dieter Enders; Andreas Haertwig; Jan Runsink

Publisher
John Wiley and Sons
Year
1998
Tongue
English
Weight
467 KB
Volume
1998
Category
Article
ISSN
1434-193X

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โœฆ Synopsis

Dipolar cycloaddition / Nitrile oxides / CฯชO bond cleavage / Nitro alkenes An enantioselective synthesis of N-protected amino diols has

Subsequent diastereo-and regioselective cycloaddition reactions to highly substituted 4,5-isoxazolines 5a-e, 8a, b been accomplished by employing a diastereoselective interand intramolecular 1,3-dipolar cycloaddition reaction of (52-81%) and reductive ring opening led -after cleavage of the auxiliary -to amino diols 13, 14 in good overall yields optically active nitrile oxides as a key step. The nitro alkane starting materials were obtained by diastereoselective oxa (27-40%, over five steps) and with excellent diastereomeric and enantiomeric excesses (de,ee ี† 96%). Michael addition of (1R,2S)-(-)-N-formylnorephedrine (1) to aliphatic (E)-nitro alkenes 2, 6a, b (de = 96 -ี† 98%).

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โœ Dieter Enders; Ilka Meyer; Jan Runsink; Gerhard Raabe ๐Ÿ“‚ Article ๐Ÿ“… 2010 ๐Ÿ› John Wiley and Sons โš– 32 KB ๐Ÿ‘ 1 views

Diastereo-and Enantioselective Synthesis of โˆ† 2 -1,2,4-Oxadiazolines by 1,3-Dipolar Cycloaddition of Nitrile Oxides with Chiral Hydrazones. -1,3-Dipolar cycloaddition of phenyl nitrile oxide with chiral hydrazones (I) affords โˆ† 2 -1,2,4-oxadiazolines (III) with low to excellent diastereoselectiviti