Novel D-pi-A chromophores based on the fulvene accepting moiety.

[reaction: see text] Novel D-pi-A chromophores based on the fulvene accepting moiety and p-dimethylamino phenyl and 1,3-dithiole-2-ylidene donor moieties have been prepared. The X-ray structures of two representative derivatives have been determined. Examination of the UV-visible spectra and cyclic voltamperometry data revealed remarkable sensitivity of the electronic structure of these derivatives to substituents at the cyclopentadiene ring.

An alternative route for Carboni-Lindsey reaction: N,N cycloaddition of an alkene to s-tetrazine.

Quantum mechanical calculations show that N,N cycloaddition of alkenes and alkynes to s-tetrazines is possible as an alternative to the well-known C,C cycloaddition (Carboni-Lindsey reaction). Formation of 1,2,4-triazole derivatives (formal product of N,N cycloaddition) along with the pyrazole (formal product of C,C cycloaddition) corroborates this theoretical prediction.