Ammonia and Amine Addition

The addition of ammonia and amines to unsaturated hydrocarbons, called hydroa-mination, is a desirable but difficult reaction. Only activated multiple bonds react readily in hydroamination to yield amines in an equilibrium reaction. It is necessary, therefore, to use catalysts in the transformation of nonactivated compounds. 

One possible way to promote hydroamination is to activate the reacting ammonia or amine.288-291 Alkali metals were found to be useful catalysts. Even in the catalyzed addition of ammonia to simple alkenes, however, drastic reaction conditions are 

The addition is more effective, allowing less severe reaction conditions if the metal amides are preformed,294 or generated in situ from alkyllithium and the amine in the presence of /V,/V,/V, /V -tetramethylethylenediamine.295 Styrenes react under very mild conditions 296 

The feasibility of acid-catalyzed direct hydroamination has been demonstrated. Acidic zeolites afford, at low conversions, highly selective formation of ethyla-mine,297,298 isopropylamine,298 and ferf-butylamine,298-301 in the reaction of ammonia with ethylene, propylene, and isobutylene, respectively. Amine formation is explained as a reaction of surface carbocation intermediates with adsorbed or 

A few examples are known using homogeneous transition-metal-catalyzed additions. Rhodium(III) and iridium(III) salts catalyze the addition of dialkylamines to ethylene.302 These complexes are believed to activate the alkene, thus promoting hydroamination. A cationic iridium(I) complex, in turn, catalyzes the addition of aniline to norbornene through the activation of the H—N bond.303 For the sake of comparison it is of interest to note that dimethylamino derivatives of Nb, Ta, and Zr can be used to promote the reaction of dialkylamines with terminal alkenes.304 In this case, however, C-alkylation instead of /V-alkylation occurs. 

---