Synthesis of amines via organoborane chemistry

Organoboranes have proven to be valuable in organic synthesis. They are readily available due to the facile reaction of olefins, dienes and acetylenes with a variety of hydroborating agents. In addition to their ready availability, the organoboranes tolerate a wide variety of functional groups and exhibit defined reaction stereospecificity which has resulted in a number of new syntheses. The boron atom in organoboranes can be readily converted into a wide variety of organic functional groups under mild conditions via stereospecific rearrangements. Many of the borane rearrangements involve anionotropic rearrangements of appropriately substituted organoborate complexes; generally, an alkyl group migrates from an electron-rich atom to an electron-deficient neighboring atom. The reaction has been used to prepare a large variety of organic molecules including those in which the migration terminus is a nitrogen atom. The nature of the leaving groups and the groups attached to nitrogen have been varied extensively. Chloramine has been shown to be one of the best amination reagents but its use in amination reactions is complicated by the fact that it is difficult to prepare and it is unstable. Amination reactions are also complicated by the fact that simple hydroboration reactions are regioselective but not regiospecific which often leads to isomeric mixtures. Solutions to these problems are presented in this thesis; they involve the in situ generation of chloramine and/or alkylchloramines and the utilization of regiospecific hydroborating agents. These methods have been developed and successfully applied to the syntheses of dialkylamines, isomerically pure primary and secondary amines, diamines and amino acids. As a part of a continuing program involving the syntheses of nitrogen-13 labeled amino derivatives as diagnostic agents for positron emission tomography, we extended the new, convenient, and easy to manipulate, one-pot amination reaction to the syntheses of isomerically pure nitrogen-13 labeled diamines and amino acids.