Synthesis and screening of mono- and di-aryl technetium and rhenium metallocarboranes. A new class of probes for the estrogen receptor.

A series of mono and diaryl rhenium(I)-carborane derivatives were prepared using microwave heating and screened for their affinity for two isoforms of the estrogen receptor (ER). The rhenacarborane derivative [(RR′C2B9H9)Re(CO)3]− (R = p-PhOH, R′ = H), which was generated by taking advantage of a recently discovered cage isomerization process, and the neutral nitrosated analogue [(RR′C2B9H9)Re(CO)2(NO)] (R = p-PhOH, R′ = H) showed the highest affinities of the compounds screened. As a result, the 99mTc analogue of one of the leads was produced in high yield (84%) and specific activity in a manner that is suitable for routine production in support of future preclinical and molecular imaging studies.