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Asymmetric Synthesis of α-Aminophosphonic Acids by Cycloaddition of N-Glycosyl-C-dialkoxyphosphonoylnitrones

✍ Scribed by Andrea Vaseila; Robert Voeffray


Book ID
102857941
Publisher
John Wiley and Sons
Year
1982
Tongue
German
Weight
823 KB
Volume
65
Category
Article
ISSN
0018-019X

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✦ Synopsis


Abstract

Addition of dialkyl phosphites to the nitrone 6, formed in situ from the oxime 5 and formaldehyde gave the hydroxylamines 7 (86%) and 8 (88%), which reacted with p‐benzoquinone in the presence of ethylene via the C‐dialkoxyphosphonoylnitrones 9 and 10 to yield the cycloaddition products 1114 (80–85%) with a diastereoselectivity of about 50%. The cycloaddition products were transformed into the monoisopropylidene derivatives 1518 and the diacetates 1922. Comparison of the NMR spectra and the specific rotations of the compounds 1922 with those of the corresponding α‐ammo‐acid derivatives 2326 of known configuration indicated preferential formation of the L‐isomers. The cycloaddition products were transformed in good yield into the L‐α‐aminophosphonic acids 29, 30, 36, and 39.


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