The Effect of Fused Rings on the Spectral and Electrochemical Properties of Bis-Fused 1,4-Diacetyl-1,4-dihydropyrazines

A series of 1,4-diacetyl-1,4-dihydropyrazines fused with two bornene, cyclopentene, and cyclohexene rings were prepared by the reduction of the corresponding pyrazines with zinc powder in the presence of acetic anhydride. Cyclic voltammetry measurements revealed that the oxidation potentials of the dihydropyrazines decrease in the order of cyclohexene-, bornene-, and cyclopentene-fused derivatives. This trend is in harmony with that of the bathochromic shifts in their UV absorptions.