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Abstract: Four new chiral organolanthanide amidate complexes have been readily prepared in good yields via silylamine elimination reaction between Ln[N(SiMe3)2]3 (Ln = Sm, Y, Yb) and chiral amidate ligands, (R)-2-(mesitoylamino)-2′-methoxy-6,6′-dimethyl-1,1′-biphenyl (1H) and (R)-2-(mesitoylamino)-2′-dimethylamino-6,6′-dimethyl-1,1′-biphenyl (2H). The steric effect of the ligand coupled with the size effect of the lanthanide ion plays an important role in complex formation. For example, treatment of 1H with half equiv of Sm[N(SiMe3)2]3 gives the C 2-symmetric bis-ligated amidate complex (σOMe:κO:κN-1)2SmN(SiMe3)2 (3) in 75% yield, while reaction of 1H or 2H with half equiv of Ln[N(SiMe3)2]3 (Ln = Y, Yb) affords the C 1-symmetric bis-ligated amidate complexes [(κO:κN-1)(σOMe:κO:κN-1)]LnN(SiMe3)2 (Ln = Y (4), Yb (5) and the C 1-symmetric mono-ligated amidate complex (σNMe2:κO:κN-2)Y[N(SiMe3)2]2 (6), respectively, in good yields. These organolanthanide amidate complexes have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. They are active catalysts for asymmetric hydroamination/cyclization of aminoalkenes and ring-opening polymerization of rac-lactide, affording cyclic amines in excellent conversions with good ee values and isotactic-rich polylactides, respectively. [Copyright &y& Elsevier]

Abstract: A new series of organo-titanium complexes have been prepared from the reaction between Ti(NMe2)4 and C 2-symmetric ligands, (R,R)-11,12-bis(pyrrol-2-ylmethyleneamino)-9,10-dihydro-9,10-ethanoanthracene (1H2), and (R,R)-bis(diphenylthiophosphoramino)-9,10-dihydro-9,10-ethanoanthracene (2H2), (R,R)-11,12-bis(mesitylenesulphonylamino)-9,10-dihydro-9,10-ethanoanthracene (3H2) and (R,R)-bis(diphenylthiophosphoramino)-1,2-cyclohexane (4H2). Treatment of Ti(NMe2)4 with 1 equiv of 1H2 gives, after recrystallization from a benzene solution, the binuclear double helicate titanium amide (1)2[Ti(NMe2)2]2⋅(5) in 71% yield. While under similar reaction conditions, reaction of Ti(NMe2)4 with 1equiv of 2H2, 3H2 or 4H2 gives, after recrystallization from a toluene or benzene solution, the mononuclear single helicate titanium amides (2)Ti(NMe2)2 (6), (3)Ti(NMe2)2 (7) and (4)Ti(NMe2)2 (8), respectively, in good yields. All new compounds have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of complexes 5–8 have further been confirmed by X-ray diffraction analyses. The titanium amides are active catalysts for the polymerization of rac-lactide, leading to the isotactic-rich polylactides. [Copyright &y& Elsevier]

Abstract: Five group 4 metal complexes (1)2Zr(NMe2)2 (5), (2)2Ti(NMe2)2 (6), (2)2Zr(NMe2)2 (7), (3)2Zr (8) and (4)2Ti(NMe2)2 (9) have been readily prepared from the reaction between M(NMe2)4 (M=Ti, Zr) and chiral binaphthyldiamine-based ligands, (R)-2,2′-bis(diphenylthiophosphoramino)-1,1′-binaphthyl (1H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(diphenylthiophosphoramino)-1,1′-binaphthyl (2H2), (R)-5,5′,6,6′,7,7′,8,8′-octahydro-2,2′-bis(methanesulphonylamino)-1,1′-binaphthyl (3H2), and C 1-symmetric ligand, (R)-2-(mesitylenesulphonylamino)-2′-(dimethylamino)-1,1′-binaphthyl (4H). All the complexes have been characterized by various spectroscopic techniques, elemental analyses and X-ray diffraction analyses. The zirconium amides are active catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in good yields with moderate ee (enantiomeric excess) values. [Copyright &y& Elsevier]

Abstract: A new series of titanium(IV) and zirconium(IV) amides have been prepared from the reaction between M(NMe2)4 (M=Ti, Zr) and C 2-symmetric ligands, (R)-2,2′-bis(pyridin-2-ylmethylamino)-6,6′-dimethyl-1,1′-biphenyl (2H2), (R)-2,2′-bis(pyrrol-2-ylmethyleneamino)-6,6′-dimethyl-1,1′-biphenyl (3H2), (R)-2,2′-bis(diphenylphosphinoylamino)-6,6′-dimethyl-1,1′-biphenyl (4H2), (R)-2,2′-bis(methanesulphonylamino)-6,6′-dimethyl-1,1′-biphenyl (5H2), (R)-2,2′-bis(p-toluenesulphonylamino)-6,6′-dimethyl-1,1′-biphenyl (6H2), and C 1-symmetric ligands, (R)-2-(diphenylthiophosphoramino)-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (7H) and (R)-2-(pyridin-2-ylamino)-2′-(dimethylamino)-6,6′-dimethyl-1,1′-biphenyl (8H), which are derived from (R)-2,2′-diamino-6,6′-dimethyl-1,1′-biphenyl. Treatment of M(NMe2)4 with 1 equiv. of N4-ligand, 2H2 or 3H2 gives, after recrystallization from an n-hexane solution, the chiral zirconium amides (2)Zr(NMe2)2 (9), (3)Zr(NMe2)2 (11), and titanium amide (3)Ti(NMe2)2 (10), respectively, in good yields. Reaction of Zr(NMe2)4 with 1 equiv of diphenylphosphoramide 4H2 affords the chiral zirconium amide (4)Zr(NMe2)2 (12) in 85% yield. Under similar reaction conditions, treatment of Ti(NMe2)4 with 1 equiv. of sulphonylamide ligand, 5H2 or 6H2 gives, after recrystallization from a toluene solution, the chiral titanium amides (5)Ti(NMe2)2·0.5C7H8 (13·0.5C7H8) and (6)Ti(NMe2)2 (15), respectively, in good yields, while reaction of Zr(NMe2)4 with 1 equiv. of 5H2 or 6H2 gives the bis-ligated complexes, (5)2Zr (14) and (6)2Zr (16). Treatment of M(NMe2)4 with 2 equiv. of diphenylthiophosphoramide ligand 7H or N3-ligand 8H gives, after recrystallization from a benzene solution, the bis-ligated chiral zirconium amides (7)2Zr(NMe2)2 (17) and (8)2Zr(NMe2)2 (19), and bis-ligated chiral titanium amide (8)2Ti(NMe2)2 (18), respectively, in good yields. All new compounds have been characterized by various spectroscopic techniques, and elemental analyses. The solid-state structures of complexes 10, 12, 13, and 17–19 have further been confirmed by X-ray diffraction analyses. The zirconium amides are active catalysts for the asymmetric hydroamination/cyclization of aminoalkenes, affording cyclic amines in good to excellent yields with moderate ee values, while the titanium amides are not. [Copyright &y& Elsevier]

Abstract: Two new chiral organoyttrium amidate complexes 1 -Y[N(SiMe3)2]2 ( 3 ) and 2 -Y[N(SiMe3)2]2·C6H12 ( 4 ·C6H12) have been readily prepared in good yields by silylamine elimination reaction between Y[N(SiMe3)2]3 and chiral binaphthyl-based amidate ligands, (R)-2,2′-bis(mesitoylamino)-1,1′-binaphthyl (1) and (S)-2-(mesitoylamino)-2′-(dimethylamino)-1,1′-binaphthyl (2), respectively. Complexes 2 and 3 have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. Complexes 3 and 4 are active catalysts for the polymerization of rac-lactide, leading to the isotactic-rich polylactides. [ABSTRACT FROM AUTHOR]

A highly enantioselective group 5 metal amide catalyst system is reported for the hydroaminoalkylation of secondary amines to give chiral amines in good yields with excellent ee values (up to 93%) by loading of 5% precatalyst. [ABSTRACT FROM AUTHOR]