ISSN:
1434-193X
Keywords:
Amino alcohols
;
Asymmetric synthesis
;
Oxa Michael addition
;
1,3-Dipolar cycloaddition
;
Nitrile oxides
;
C-O bond cleavage
;
Nitro alkenes
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
An enantioselective synthesis of N-protected amino diols has been accomplished by employing a diastereoselective inter- and intramolecular 1,3-dipolar cycloaddition reaction of optically active nitrile oxides as a key step. The nitro alkane starting materials were obtained by diastereoselective oxa Michael addition of (1R,2S)-(-)-N-formylnorephedrine (1) to aliphatic (E)-nitro alkenes 2, 6a, b (de = 96 - ≥ 98%). Subsequent diastereo- and regioselective cycloaddition reactions to highly substituted 4,5-isoxazolines 5a-e, 8a, b (52-81%) and reductive ring opening led - after cleavage of the auxiliary - to amino diols 13, 14 in good overall yields (27-40%, over five steps) and with excellent diastereomeric and enantiomeric excesses (de,ee ≥ 96%).
Type of Medium:
Electronic Resource
