Cycloaddition precursor cyclopentadiene ring

We became interested in this area of chemistry because we wished to prepare some new and highly electrophilic 2//-azirines with potential for use as dienophiles in the Diels-Alder reaction. Vinyl azides appeared to be the most promising precursors. Previously there had been only one report of the cycloaddition of 2H-azirines to a simple diene (cyclopentadiene) although highly activated dienes such as tetraphenylcyclopentadie-none and 1,3-diphenylisobenzofuran had been used to intercept some transient 2H-azirines. Our investigations led to the preparation of several new 2ff-azirines. Cycloaddition reactions with these provided access to some novel fused-ring aziridines. An outline of the results is included in Sections 6.2 and 6.3. 

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