Synthesis of push-pull chromophores by the sequential [2+2] cycloaddition of 1-azulenylbutadiynes with tetracyanoethylene and tetrathiafulvalene

Azulene-substituted butadiynes have been prepared by Cu-mediated cross- and homo-coupling reactions. The azulene-substituted butadiynes reacted with tetracyanoethylene in a formal [2 + 2] cycloaddition reaction to afford the corresponding 1,1,4,4-tetracyanobutadiene chromophores, in excellent yields. Further [2 + 2] cycloaddition with TTF and TCNE gave novel donor-acceptor chromophores and novel azulene-substituted 6,6-dicyanofulvene derivatives.