Microwave-Assisted Synthesis of 3,1,2- and 2,1,8-Re(I) and ^99mTc(I)−Metallocarborane Complexes

Abstract

Microwave heating was used to prepare eta5-rhenium carborane complexes in aqueous reaction media. For carboranes bearing sterically demanding substituents, isomerization of the cage from 3,1,2 to 2,1,8 derivatives occurred concomitantly with complexation. Microwave heating was equally effective at the tracer level using technetium-99m, affording access to a new class of synthons for designing novel molecular imaging agents.

Polyhedral Boranes for Medical Applications: Current Status and Perspectives

“…High-yield preparative methods for the synthesis of -(M = Re, 99 Tc) were developed. [161] More recently, the radiolabeling of the nido-carborane derivatives with 99m Tc in water under weakly basic conditions was described [162][163][164] (Scheme 17).…”

Microwave-Assisted Synthesis of Organometallic Complexes of 99mTc(CO)3 and Re(CO)3: Its Application to Radiopharmaceuticals

“…Microwave technology has been successfully applied to enhance radiolabeling reactions. [4][5][6] When microwave is used as a source of energy, the reactions proceed in a short time and in much higher yields than those performed under the conventional thermal conditions.…”

Nucleoside-metallacarborane conjugates - synthesis of a uridine - bearing 3,3,3-(CO)3-closo-3,1,2-ReC2B9H10 complex

“…Tc). [8][9][10][11][12][13][14] Rhenacarboranes were prepared several years ago. 11,12,[14][15][16][17][18][19][20] 131 I-rhenacarborane is enzymatically stable and is able to cross the blood-brain barrier (BBB) by transmembrane diffusion, allowing this compound to accumulate in the brain in substantial amounts.…”

“…[8][9][10][11][12][13][14] Rhenacarboranes were prepared several years ago. 11,12,[14][15][16][17][18][19][20] 131 I-rhenacarborane is enzymatically stable and is able to cross the blood-brain barrier (BBB) by transmembrane diffusion, allowing this compound to accumulate in the brain in substantial amounts. 21 The biomedical applications of icosahedral carboranes make use of their extraordinary hydrophobicities when employed as substituents in biomolecules, their apparent invisibility to know enzyme systems and their boron content, which is suitable for Boron Neutron Capture Therapy (BNCT There is an entire area of radiopharmaceuticals devoted to the application of radiolabeled nucleic acids, and the use of the components of nucleic acids, nucleosides and nucleotides, may be advantageous.…”