PAPER: Transition-metal catalyzed asymmetric 1,3-dipolar cycloaddition reactions between alkenes and nitrones

Gothelf, K. V.; Jørgensen, K. A.

J. Org. Chem. 1994, 59, 5687–5691, doi: 10.1021/jo00098a029

Abstract

A transition-metal-catalyzed enantioselective 1,3-dipolar cycloaddition reaction between alkenes
and nitrones has been developed employing 10 mol % of a chiral titanium catalyst generated in
situ from Ti(i-OPr)zClz and chiral diols. Diastereofacial discrimination in favor of the ex0 isomer
was achieved in up to a 955 ratio. Isoxazolidines with an optical purity of up to 62% ee are obtained
from this reaction. By precipitation of a racemate of one of the isoxazolidines an optical purity of
>95% ee is obtained.

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