We describe the syntheses of half-sandwich complexes of the type [(η5-Cp(CONH-R))M(CO)3] with M = Re or 99mTc. The R group represents different tri-peptides (tpe) which display high binding affinities for oligopeptide transporters PEPT2. The 99mTc complexes were prepared directly from [99mTc(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 [(η5-Cp)99mTc(CO)3] tag. We synthesized the Diels–Alder product [(HCpCONH-tpe)2] from Thiele's acid [(η5-HCpCOOH)2] via double peptide coupling. The Re-complexes [(η5-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 99mTc-complexes is confirmed by chromatographic comparison with the corresponding rhenium complexes, fully characterized by spectroscopic techniques.
我们描述了[(η5-Cp(CONH-R))M(CO)3]型半三明治复合物的合成,其中M = Re或99mTc。R基团代表不同的三肽(tpe),它们对寡肽转运蛋白PE
PT2具有高结合亲和力。99mTc复合物直接由[99mTc(OH2)3(CO)3]+和Diels-Alder二聚体、
环戊二烯衍
生物肽在
水中制备。这种方法证实了
金属介导的反式Diels-Alder反应不仅可用于制备小分子,还可用于制备带有[(η5-Cp)99mTc(CO)3]标签的肽。我们通过双肽偶联从Thiele酸[(η5-HCpCOOH)2]合成了Diels-Alder产物[(HCpCONH-tpe)2]。通过将[(Cp-COOH)Re(CO)3]直接连接到从
SPPS获得的肽的N端,获得了Re复合物[(η5-CpCONH-tpe)Re(CO)3]。通过与相应的
铼复合物进行色谱比较,证实了99mTc复合物的真实性,并通过光谱技术对其进行了充分表征。