Synthesis of 2,3,4,5-Tetra(2-thienyl)cyclopentadienone Exhibiting Considerable Substituent Effects and Synthetic Utility.

2,3,4,5-Tetra(2-thienyl)cyclopentadienone and the related compounds, here first synthesized, show large bathochromic shift of visible absorptions and appreciably higher amphoteric redox properties than tetraphenylcyclopentadienone; 2-thienyl groups at 2,5-positions exert stronger substituent effects than those at 3,4-positions.