1,3-Dipolar cycloadditions to methylenespiro[2.2]pentane: a complementary access to spiro cyclopropanated azaheterocycles

Abstract

The domino cycloaddition–thermal rearrangement of nitrile oxides and methylenespiro[2.2]pentane gives 5-azaspiro[2.5]oct-6-en-8-one derivatives; with a nitrone the process complements the one using bi(cyclopropylidene) for the synthesis of α-spiro cyclopropanated heterocyclic ketones.