Rearrangement of isoxazoline-5-spiro derivatives. 1. Synthesis of 4, 5-dihydroisoxazole-5-spirocyclopropanes and their rearrangement to 5, 6-dihydro-4-pyridones

A Guarna, A Brandi, F De Sarlo, A Goti…

Index: Guarna, Antonio; Brandi, Alberto; Sarlo, Francesco, De; Goti, Andrea; Pericciuoli, Fabio Journal of Organic Chemistry, 1988 , vol. 53, # 11 p. 2426 - 2429

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Citation Number: 25

Abstract

The title spiroheterocycles 3 are prepared by cycloaddition of nitrile oxides to methylenecyclopropane or its ring-substituted derivatives. Thermolysis of the cycloadducts 3 affords, presumably via N-0 bond homolysis, the title pyridones 7 besides minor amounts of the isomeric enaminones 6: the amounts of 6 relative to 7 are reduced when thermolysis is carried out by FVT rather than in solution. Similar results are obtained by photolysis of 3b ...