Lanthanocene catalyzed hydroamination

Figure 11.2 Proposed stereomodeisforthe lanthanocene catalyzed hydroamination/cyclization of...

Scheme 11.20 Stereomodel for the lanthanocene catalyzed hydroamination/cyclization of aminodienes. The silicon linker bridging the two cyclopentadienyl ligands was omitted for the sake of clarity.

Scheme 2 Lanthanocene-catalyzed intramolecular hydroamination of terminal aminoalkenes...

Hydroamination of Simple, Nonactivated Alkenes 349 Table 11.1 Lanthanocene catalyzed aminoalkene hydroamination/cyclization [35, 36]. 

Organolanthanide-catalyzed hydroamination of conjugated dienes is a facile process due to the transient formation of an 7 -allyl intermediate, which forms E/Z-vinylpyrrolidines and vinylpiperidines upon protonation, and, under certain conditions, also aUyl isomers (Fig. 11, Scheme 12). Cychzations with lanthanocenes... 

The bulk of the studies on intramolecular hydroamination of alkenes catalyzed by lanthanide complexes have been conducted using lanthanocene complexes or half-sandwich lanthanide complexes. The prototypical cyclizations of aminoalkenes to form five- and six-membered rings are shown in Equation 16.61. These reactions occur with exclusive Markovnikov selectivity. These reactions have also been conducted using arylamines, as shown in Equation 16.62. The intramolecular reactions of amines catalyzed by certain lanthanide complexes occur with 1,1- and 1,2-disubstituted olefins (Equation 16.63), although such reactions require high temperatures. 

The first chiral rare earth metal-based hydroam-ination catalysts were reported in 1992 using chiral lanthanocene. Organolanthanide complexes catalyze regios-elective intermolecular hydroamination of alkenes, alkynes. 

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