Internal alkene hydroaminations catalyzed by zirconium(IV) complexes and asymmetric alkene hydroaminations catalyzed by yttrium(III) complexes

The thiophosphinic amide 2 was prepared in 68% yield by the reaction of 2,2-dimethyl-1,3-propanediamine with diisopropylchlorophosphine followed by the addition of sulfur. Attachment of the proligand 2 to zirconium was achieved by direct metalation with Zr(NMe2)(4) in benzene-d(6) or toluene-d(8) to afford complex 3 via elimination of dimethylamine. The neutral Zr(IV) complex 3 has been shown to be an effective precatalyst for intramolecular alkene hydroaminations that provide cyclic amines in good to excellent yields. A variety of chiral ligands (20, 22, 24, and 25-30) were prepared for asymmetric internal alkene hydroaminations. Metalation of chiral ligands to yttrium was accomplished with Y[N(TMS)(2)](3) in benzene-d(6) or toluene-d(8) to give complexes. Treatment of 7 with 5 mol% of 33 in benzene-d(6) (25 degrees C, 18 h) or toluene-d8 (25 degrees C, 15 h) afforded 2,4,4-trimethylpyrrolidine 14 in 95% yield (61% ee).