Cationic group 4 metal hydroamination catalysts

Tire first chiral group 4 metal catalyst system for asymmetric hydroamination/ cyclization of aminoalkenes was based on the cationic aminophenolate complex (S) 45 [85[. Secondary aminoalkenes reacted readily to yield hydroamination products with enantioselectivities of up to 82% ee (Scheme 11.14). For catalyst solubility reasons, reactions were commonly performed at 100 °G in bromobenzene using... 

Neutral group 4 metal complexes appear to possess a relatively broad scope for catalytic hydroaminations. They have been employed for the intramolecular hydroamination of alkynes [2], allenes [3], and alkenes [4] as well as the inter-molecular hydroaminations of alkynes [5] and allenes [6]. Primary aryl- and alkylamines readily react, but secondary amines have posed a greater challenge for this type of transformation with neutral catalysts [7]. For the reactions of the latter, cationic Zr and Ti complexes have been employed in intramolecular cyclizations of aminoalkenes [8]. Very recent work suggests that substrates that are difficult to hydroaminate may favor hydroaminoalkylations instead (Scheme 13.2) [9]. 

---