Indium complexes carboxylates

DOTA is of particular interest as a BFC for radiolabeling of small BMs with yttrium and lanthanide isotopes. The macrocyclic framework is well organized so that it forms yttrium and indium complexes with high thermodynamic stability and kinetic inertness. The pXa values of the carboxylic groups are in the range 2-5. Lower pKa values result in less competition from protons, high stability of the metal complex, and minimum acid-assisted demetallation, even... 

Methylisoxazole-5-carboxylic acid was converted into the corresponding 5-carboxamides and 5-(l/7-pyrazol-l-ylcarbonyl) derivatives in satisfactory yields by treatment with thionyl chloride and amines or pyrazoles <2002SC425>. A three-component assembly of isoxazole-5-carboxylic acid chloride, 1,1-dimethylallene, and bis-pinacolatodiboron, catalyzed by a phosphine-free palladium complex, gave 2-acylallylboronate derivatives regiose-lectively (Equation 47) <2003JA12576>. On the other hand, a mild procedure allowed the preparation of /3,7-unsaturated ketones by simple reaction of 3-aryl-5-methylisoxazole-4-carboxylic acid chlorides with allyl bromide and indium in DMF (Equation 48) <1997TL8745>. 

Both irradiation by visible light and pyridine are required for the above insertion. The same carboxylate complexes can be prepared by reaction of acetic acid with either the alkyl(aryl)indium(III) porphyrins or the aquohydroxoindium(III) porphyrins. 

As previously mentioned, the aluminum carboxylate derivative has been characterized in situ. The indium carboxylate complexes exhibit typical NMR spectra expected for hexa-coordinated systems. The X-ray crystal structure of In(OEP)C02CH3 2CHCI3 has been solved Figure 11 presents the ORTEP view of this complex. 

Comparisons to the known structure of indium DTPA and to other divalent metal DTPA bis-amide complexes indicate that the indium cation binds to the three amine nitrogen atoms, the four carboxylate oxygen atoms, and the one carboxairdde oxygen atom of the DTPA monoamide ligand. Addition of an acidic In chloride solution to a ly-ophilized DTPA-octreotide pellet at room temperature readily fomis In DTPA-octreotide, known clinically as OctreoScan. In a rat model of pancreatic carcinoma In DTPA-octreotide showed clear visualization of the tumors and rapid, primarily renal, clearance of the radiophamiaceutical/ Moreover, pretreatment with 1 mg of octreotide prevents uptake of " in DTPA-octreotide in the tumors and adrenal glands, an observation that verifies that this radiolabeled peptide binds to receptor sites. 

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