Spiroheterocycles via Regioselective Cycloaddition Reactions of Nitrile Oxides with 5-Methylene-1H-pyrrol-2(5H)-ones

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Contents Vol 63(3)

doi:10.1071/CH09479

Spiroheterocycles via Regioselective Cycloaddition Reactions of Nitrile Oxides with 5-Methylene-1H-pyrrol-2(5H)-ones

Nicola J. Beattie ^A, Craig L. Francis ^A, Andris J. Liepa ^A, G. Paul Savage ^A ^B

^A CSIRO Molecular and Health Technologies, Private Bag 10, Clayton South MDC, Vic. 3169, Australia.
^B Corresponding author. Email: paul.savage@csiro.au





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Australian Journal of Chemistry 63(3) 445–451 http://dx.doi.org/10.1071/CH09479
Submitted: 9 September 2009 Accepted: 21 October 2009 Published online: 26 March 2010

Abstract

Substituted 5-methylene-1H-pyrrol-2(5H)-ones underwent a 1,3-dipolar cycloaddition reaction with nitrile oxides to give the corresponding spiro heterocycles. Critical to this reaction was the development of a biphasic system for base-induced dehydrohalogenation of hydroximoyl chlorides, to give nitrile oxides, in the presence of a base-sensitive dipolarophile. A substituted N-tolyl 5-methylene-1H-pyrrol-2(5H)-one exhibited atropisomerism, which in turn led to a 4:1 facial selectivity during cycloaddition.