Unusual Condensation of 3-Thia[5](1,1‘)ferrocenophane-1,5-dione with Glyoxal. Formation of [1.1](2,3)Thiopheno(1,1‘)ferrocenophane-1,7-dione

When 3-thia [5](1,1‘)ferrocenophane-1,5-dione 2 was condensed with glyoxal in the presence of sodium
ethoxide, a thiophene-2,3-diyl derivative 3 was obtained as a sole product, instead of the expected 2,5-substituted compound 1.

当3-硫杂[5](1,1′)二茂铁环蕃-1,5-二酮2与乙二醛在乙醇钠存在下发生缩合反应时，得到噻吩-2,3-二基衍生物3作为唯一产物，而非预期的2,5位取代化合物1。