Synthesis, NMR, and X-ray crystallographic analysis of C-hydrazino-C-carboxycarboranes: versatile ligands for the preparation of BNCT and BNCS agents and (99m)Tc 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 structures of the monosubstituted ortho-carborane, 1-[(N,N'((tert-butyloxy)carbonyl)hydrazino)]-1,2-dicarba-closo-dodecaborane (8) [a = 21.213(6) A, b = 10.498(3) A, c = 9.866(2) A, alpha = gamma = 90 degrees, beta = 90.529(4) degrees ] and the bifunctional para-carborane 1-[(N,N'((tert-butyloxy)carbonyl)hydrazino)]-1,12-dicarba-closo-dodecaborane-12-carboxylic acid (3) [a = 12.744(10) A, b = 12.875(9) A, c = 14.767(9) A, alpha = beta = gamma = 90 degrees ] were obtained. Intermolecular hydrogen bonding was a dominant packing feature in both structures. The reported compounds represent a unique class of bifunctional carboranes that can be used in peptidomimetic research and as synthons to prepare novel radiopharmaceuticals and boron neutron capture therapy/boron neutron capture synovectomy (BNCT/BNCS) agents.
Valliant
John F
JF
Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1, Canada. valliant@mcmaster.ca
Sogbein
Oyebola O
OO
Morel
Pierre
P
Schaffer
Paul
P
Guenther
Katharina J
KJ
Bain
Alex D
AD
D001880:Boranes / Q000032:analysis* / Q000138:chemical synthesis*; D001896:Boron Compounds; D002384:Catalysis; D018360:Crystallography, X-Ray; D006834:Hydrazines / Q000032:analysis* / Q000138:chemical synthesis*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009502:Neutrons; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis* / Q000737:chemistry*; D013667:Technetium / Q000737:chemistry*
C465080:1-((N,N'((tert-butyloxy)carbonyl)hydrazino))-1,12-dicarba-closo-dodecaborane-12-carboxylic acid; C465078:1-((N,N'((tert-butyloxy)carbonyl)hydrazino))-1,2-dicarba-closo-dodecaborane; D001880:Boranes; D001896:Boron Compounds; D006834:Hydrazines; D008024:Ligands; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; D013667:Technetium