(ETA(5)-CYCLOPENTADIENYL)FE(CO)(2)-COMPLEXES OF SULFONAMIDE ANIONS - ACYLATION OF THE AMINO GROUP IN THE SULFANILAMIDE COMPLEX AND ITS RELEVANCE TO THE PROTEIN LABELING

Illumination with visible light of [CpFe(CO)(2)I] (Cp = eta(5)-C5H5) w ith NH2SO2C6H4-p-R (R = Me, NO2, NH2) in benzene in the presence of di isopropylamine gives [CpFe(CO)(2)NHSO2C6H4-p-R] in 62-91% yield. The p rimary amino group in [CpFe(CO)(2)NHSO2C6H4-p-NH2] was acylated by tre atment of this complex with neat carboxylic acid anhydrides (acetic, p ropionic and isobutyric) or with carboxylic acid (acetic, iodoacetic, beta-maleimidopropionic) and 1-[3-(dimethylamino)propyl]-3-ethyl-carbo diimide (EDC) in aqueous solutions at pH 5-6 at room temperature. The latter reaction shows that [CpFe(CO)(2)NHSO2C6H4-p-NH2] can be used as an IR-detectable metallo-carbonyl reagent labelling the COOH groups i n proteins and as a parent compound for a new family of reagents label ling the thiol function. (C) 1998 Elsevier Science S.A. All rights res erved.