Hydroamination

In organic chemistry, hydroamination is the addition of an bond of an amine across a carbon-carbon multiple bond of an alkene, alkyne, diene, or allene. In the ideal case, hydroamination is atom economical and green. Amines are common in fine-chemical, pharmaceutical, and agricultural industries. Hydroamination can be used intramolecularly to create heterocycles or intermolecularly with a separate amine and unsaturated compound. The development of catalysts for hydroamination remains an active area, especially for alkenes. Although practical hydroamination reactions can be effected for dienes and electrophilic alkenes, the term hydroamination often implies reactions metal-catalyzed processes. File:Examples of intermolecular hydroamination.png|alt=Prototypical intermolecular hydroamination reactions.|Prototypical intermolecular hydroamination reactions. File:Examples of intramolecular hydroamination (2).png|alt=Examples of intramolecular hydroamination.|Examples of intramolecular hydroamination. Hydroamination is well-established technology for generating fragrances from myrcene. In this conversion, diethylamine adds across the diene substituent, the reaction being catalyzed by lithium diethylamide. Intramolecular hydroaminations were reported by Tobin J. Marks in 1989 using metallocene derived from rare-earth metals such as lanthanum, lutetium, and samarium. Catalytic rates correlated inversely with the ionic radius of the metal, perhaps as a consequence of steric interference from the ligands. In 1992, Marks developed the first chiral hydroamination catalysts by using a chiral auxiliary, which were the first hydroamination catalysts to favor only one specific stereoisomer. Chiral auxiliaries on the metallocene ligands were used to dictate the stereochemistry of the product. The first non-metallocene chiral catalysts were reported in 2003, and used bisarylamido and aminophenolate ligands to give higher enantioselectivity. Hydroamination has been examined with a variety of amines, unsaturated substrates, and vastly different catalysts.