Institute of Chemistry, University of the Punjab, Quaid-e-Azam Campus 54590, Lahore, Pakistan.
Org Biomol Chem. 2014 Mar 28;12(12):1966-74. doi: 10.1039/c3ob41866a. Epub 2014 Feb 18.
We describe the syntheses of half-sandwich complexes of the type [(η(5)-Cp(CONH-R))M(CO)3] with M = Re or (99m)Tc. The R group represents different tri-peptides (tpe) which display high binding affinities for oligopeptide transporters PEPT2. The (99m)Tc complexes were prepared directly from (99m)Tc(OH2)3(CO)3 and Diels-Alder dimerized, cyclopentadienyl derivatized peptides in water. This approach corroborates the feasibility of metal-mediated retro Diels-Alder reactions for the preparation of not only small molecules but also peptides carrying a [(η(5)-Cp)(99m)Tc(CO)3] tag. We synthesized the Diels-Alder product [(HCpCONH-tpe)2] from Thiele's acid [(η(5)-HCpCOOH)2] via double peptide coupling. The Re-complexes [(η(5)-CpCONH-tpe)Re(CO)3] were obtained by attaching [(Cp-COOH)Re(CO)3] directly to the N-terminus of peptides as received from SPPS. The authenticity of the (99m)Tc-complexes is confirmed by chromatographic comparison with the corresponding rhenium complexes, fully characterized by spectroscopic techniques.
我们描述了 [(η(5)-Cp(CONH-R))M(CO)3] 型半三明治配合物的合成，其中 M = Re 或 (99m)Tc。R 基团代表不同的三肽 (tpe)，它们对寡肽转运蛋白 PEPT2 具有高结合亲和力。(99m)Tc 配合物直接由 (99m)Tc(OH2)3(CO)3 和 Diels-Alder 二聚化、环戊二烯基衍生的肽在水中制备。这种方法证实了金属介导的反 Diels-Alder 反应不仅可用于制备小分子，还可用于制备携带 [(η(5)-Cp)(99m)Tc(CO)3] 标记的肽。我们通过双肽偶联从 Thiele 酸 [(η(5)-HCpCOOH)2] 合成了 Diels-Alder 产物 [(HCpCONH-tpe)2]。通过直接将 [(Cp-COOH)Re(CO)3] 连接到从 SPPS 获得的肽的 N 末端，得到 Re 配合物 [(η(5)-CpCONH-tpe)Re(CO)3]。通过与相应的铼配合物的色谱比较以及通过光谱技术的全面表征，确证了 (99m)Tc 配合物的真实性。
