Methacryloyl isocyanate (MAI) functioned as an ambident heterodiene in
the cycloaddition reactions. Thus, enamines added not only to the acy
l isocyanato moiety, but also to the enone moiety in MAI. Regiochemist
ry of this cycloaddition markedly depended on the reaction conditions.
The pathways for the formation of products are also described.