Heterocyclic spiro-compounds from tandem cascade reaction of alkyl azides and methyl vinyl ketone

摘要

Tandem cascade reaction of one molecule of alkyl azide and four molecules of methyl vinyl ketone gives a heterocyclic compound having an 1,4-diazepine fused to a pyrazoline and spiro-linked to a dihydropyran. The tandem cascade reaction is composed of an intermolecular [3+2] dipolar cycloaddition to give a triazoline, an isomerization to a diazo compound, another intermolecular [3+2] dipolar cycloaddition to give a pyrazoline, a Michael addition, dehydration, and a [4+2] cycloaddition. [References: 13]