S. Lisac et al., FERROCENE COMPOUNDS .24. SYNTHESIS AND REACTIONS OF SOME OMEGA,OMEGA'-(1,1'-FERROCENYLENE)BIS(THIAALIPHATIC ACIDS), Croatica chemica acta, 70(4), 1997, pp. 1021-1037
Condensations of several alpha,alpha'-disubstituted 1,1'-ferrocenylene
biscarbinals (1) with mercaptoethanoic acid, 3-mercaptopropanoic acid
or 3-acetylthio-2-methylpropanoic acid in the presence of trifluoroace
tic acid have given the corresponding 1,1'-ferrocenylenebisthiaaliphat
ic acids (2-4) in 49-90% yields. Reactions of acids 2-4 with trifluoro
acetic anhydride yielded 15-29% of trans-2-oxa[3]ferrocenophanes (tran
s-8), 7-13% of [2,2]ferrocenophanes (9) and 8-15% of the ethanoferroce
nylene oligomers (10). The mechanism of the reactions is discussed.