Aminopentenes, hydroamination

The first and so far only example of catalytic asymmetric metal free hydroamination using the chiral phosphoric acid diester R) 58 was recently disclosed (Eq. 11.8) [111]. Although both selectivity and catalytic activity for the hydroamination ofthe secondary aminopentene 59 are rather low, the method itself remains very promising. 

Hydroamination with Enantiomerical Pure Amines 367 Table 11.3 Catalytic kinetic resolution of chiral aminopentenes [52, 124]. 

Zirconium The new chiral zirconium complex (98) has been shown to catalyse intramolecular hydroamination of aminopentenes CH2=CHCH2CR2CH2NH2 [R2 = Mc2, Ph2, (012)4-, -(012)5-] to afford 2-methylpyrrolidines (89-98% ee). The rate law supports the mechanism involving a reversible substrate-catalyst interaction that precedes the RLS. A new mechanism for zirconium-catalysed hydroamination has been proposed, based on kinetic isotope effects and the significant effect of isotopic substitution on enantioselectivity. ... 

Rare earth metal complexes witii stericaUy demanding tris(aryl)silyl-substituted binaphtholate ligands efficiently catalyze asymmetric hydroamination/cyclization of aminoalkenes and the kinetic resolution of a-substituted aminopentenes. The catalytic activities are comparable to... 

Several examples of organoaluminum-catalyzed hydroamination of amino-alkenes have been reported recently. The neutral amido bis(anilide) 27 [37] and the aluminum pincer diolate complex 28 [114] displayed low catalytic activity and were only applicable to gem-disubstituted aminopentenes (Fig. 7). 

A dramatic increase in reactivity was observed for the zwitterionic zirconium cyclopentadienyl-bis(oxazolidinyl)borate complex 33 [118]. The hydroamination reactions proceeded readily at room temperature, thus significantly exceeding the reactivity of most zirconium analogs. Despite the high reactivity, cyclization of the unsubstituted aminopentene did not proceed to high conversion even at high catalyst loading (Table 5, entry 10) possibly due to an autoinhibition [118]. 

Table 14 Asymmetric intramolecular hydroamination of aminopentenes using post-metallocene rare earth metal catalysts...

Table 17 Lithium amide-catalyzed asymmetric hydroamination of aminopentenes...

Table 19 Asymmetric hydroamination of aminopentenes catalyzed by zirconium complexes...

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