Synthesis, NMR, and X-ray Crystallographic Analysis of C-Hydrazino-C-Carboxycarboranes: Versatile Ligands for the Preparation of BNCT and BNCS Agents and 99mTc Radiopharmaceuticals

Protected hydrazine derivatives of ortho-, meta-, and para-carboranes were synthesized in good to excellent yields by reacting the mono-lithio salts of the respective carboranes with di-tert-butyl azodicarboxylate (DBAD). Subsequent deprotonation of the remaining carborane CH group, followed by the addition of CO(2)(g), resulted in the formation of bifunctional C-hydrazino-C-carboxycarboranes in good to excellent overall yields. Crystal …