Large-Scale Preparation of 1,1′-Ferrocenedicarboxylic Acid, a Key Compound for the Synthesis of 1,1′-Disubstituted Ferrocene Derivatives

Abstract

Efficient and simple methods for the large-scale preparation of 1,1′-ferrocenedicarboxylic acid, fc(COOH) 2 , involving the sodium salts of cyclopentadienecarboxylic methyl and ethyl esters, Na(C 5 H 4 COOR) (R = Me, Et), are presented. With fc(COOH) 2 at hand, the syntheses of various 1,1′-disubstituted compounds of the type fcX 2 (X = CH 2 OH, COCl, CON 3 , NCO, NHCOOMe, NHBoc, NH 2 ) were optimized and scaled up. The X-ray crystal structures of f c ( C O O E t ) 2 , fc(NCO) 2 • 1 / 2 C 6 H 6 , and fc-(NHCOOMe) 2 •MeOH are reported.

Towards the Next Generation of Lochmann–Schlosser Superbases: A Potassium Neopentyl/Alkoxy Aggregate used in the Tetra‐Functionalization of Ferrocene

“…[36] Short intermolecular interactions elucidate the poor solubility of 7 4 in solvents. [32] To conclude, two new mixed alkyl/alkoxy alkali metal aggregates were isolated. [32] To conclude, two new mixed alkyl/alkoxy alkali metal aggregates were isolated.…”

“…1 HNMR of this powder in [D 6 ]DMSO revealed am ixture of predominantly tetra-substituted ferrocene 6 4 [1,1',3,3'-ferrocenetetracarboxylic acid, Fc(COOH) 4 ;F c = Fe(C 10 H 10-n )],b ut also tri-and di [32] -substituted ferrocenecarboxylic acids 6 3 and 6 2 [1,1',3-ferrocenetricarboxylic acid, [33] Fc(COOH) 3 ,a nd 1,1'-ferrocenedicarboxylic acid (Fc(COOH) 2 )] in an characteristic, average ratio of approximately 78 %( 6 4 )/approximately 10 %( 6 3 )/approximately 10 %( 6 3 ). precipitate was inaccessible to further characterization;d estructive hydrolysis in deuterated benzene revealed the presence of both ferrocene and t-amyl alcohol, neopentane was not observed.…”

“…Even thought he metalation of ferrocene with 5 produced high yields of 6 4 ,i ts poor solubility (except in DMSO and DMF) made it difficult to separate it from the by-products 6 3 and 6 2 by column chromatography.H owever,a ll three compounds could be transformed into their methyl esters 7 4 [Fc(COOMe) 4 ], 7 3 [Fc(COOMe) 3 ], and 7 2 [Fc(COOMe) 2 ] [32] by reaction with trimethylsilyldiazomethane [Me 3 SiCHN 2 ] [34] in toluene or alternatively with boron trifluoride diethyl etherate in methanol [BF 3 ·OEt 2 /MeOH]. [35] Precipitated 7 4 was separated by filtration from 7 3 and 7 2 .T he lattert wo compounds were separated by columnc hromatography.C ompounds 7 4 and 7 3 are crystalline, orange solids, which could be characterized by NMR spectroscopy in deuterated chloroform.…”

Structure and Properties of Macrocyclic Nickel(II) Coordination Polymer Bearing 1,1'-Ferrocenedicarboxylate Bridging Ligand

“…[8][9][10] Although the fdc ligand has two carboxylate groups on the rigid cyclopentadienyl (Cp) rings, it is fairly flexible in binding to metal ions due to the possible rotation of Cp rings about the Cp-Fe-Cp axis.…”

“…The torsion angle of 12.63 o in the present complex 1 is close to that found in {[Zn(L2)(fdc)]·2H 2 O} n (7. . 4,9,12,13,15 In those cases, the relationship between the two 1,1'-substituents on Cp rings prefers to take a synclinal conformation. Even synperiplanar conformation is observed in some cases, where two Cp rings and substituents are eclipsed (Scheme 1).…”