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Molecules, Volume 2, Issue 3 (March 1997) – 1 article , Pages 57-61

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Open AccessArticle

Synthesis of Spiroisoxazolines by 1,3-Dipolar Cycloaddition

by Peter Micuch, Lubor Fisera, Vladimír Ondrus and Peter Ertl

Molecules 1997, 2(3), 57-61; https://doi.org/10.3390/20300057 - 8 Apr 1997

Cited by 17 | Viewed by 9095

Abstract

The cycloaddition of the chiral nitrile oxide 1 to 1-R-substituted 3,3-methylene-5,5-dimethyl-2-pyrrolidinones 2 (where R is H, n-butyl-, 1,1-dimethylethoxycarbonyl-, 1-methylethenyl- and acetyl-) proceeds regioselectively under the formation of spiroisoxazolines, namely 7-R-substituted-6-oxo-8,8-dimethyl-1-oxa-2,7-diazaspiro[4,4]non-2-enes 5 and 6. The asymmetric induction expected by the a-chiral centre of the nitrile oxide 1 was not very effective, diastereoisomers 5 and 6 were formed in an approximate 50:50 ratio. The stereoselectivity of the 1,3-dipolar cycloaddition of the arylnitrile oxide 7 with the chiral lactam 3 and the achiral lactone 4 are investigated. The attack of the 1,3-dipole occurred from the less hindered face of the dipolarophile 3 and 4, giving the major isomer 8 and 10, respectively. Full article

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Molecules, Volume 2, Issue 3 (March 1997) – 1 article , Pages 57-61

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