Vinyl-substituted azaarenes are rare and challenging substrates as dienophiles in Diels–Alder reactions; by employing Lewis acid activation, high yielding and highly selective cycloadditions with unactivated dienes are enabled.

A mild, broadly functional group tolerant methodology has been developed to access a variety of mono- and bis-carbodiimides in good yield and high purity on multigram scale. Direct addition into these versatile motifs facilitated the rapid synthesis of a library of novel amidinines, guanidines, and phosphaguandines.