title: Synthesis of 3-Amino-1-carboxy-o-carborane and an Improved, General Method for the Synthesis of All Three C-Amino-C-carboxycarboranes.
abstract: Amino acids of the polyhedral carboranes have potential applications in boron neutron capture therapy and in other areas of bioorganic chemistry, but simple, general methods for their synthesis are nonexistent. A general method for synthesis of C-amino-C-carboxy derivatives of o-, m-, and p-carborane is reported, starting from their respective monoacids and proceeding through nucleophilic attack by an alcohol on the intermediate C-isocyanates. Deprotection of the resulting carbamates provides a simple method for access to the C-amines. Alternatively, the C-isocyanates can be isolated for further reactions. Carbonylation of the carbamates at the remaining carboranyl CH results in high-yield production of the carbamate-protected amino acid. Another related method for the high-yield preparation of the isomeric 3-amino-1-carboxy-o-carborane is also described which makes available for the first time all four reasonably accessible members of the series.
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143-0446.
authors.forename: Ramesh A.
authors.initials: RA
authors.lastname: Kasar
authors.forename: Giselle M.
authors.initials: GM
authors.lastname: Knudsen
authors.forename: Stephen B.
authors.initials: SB
authors.lastname: Kahl