Oxazoles, nitrile ylide electrocyclizations

In an attempt to investigate this theory further, the analogous alkoxy-substituted nitrile ylides 171 were investigated. Species of this type were previously unknown but were successfully generated for this work by the thermolysis of the 4-alkoxy substituted l,3-oxazol-5-ones 170 (89). In the absence of a dipolarophile, the nitrile ylides reacted via 1,5-electrocyclization to give the isoindoles 173 [see also... 

This reaction is likely to proceed via intermediate formation of nitrile ylides 15 and their electrocyclic ring closure as 1,5-dipoles (cf p 144) yielding the oxazole system [69a]. 

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