Two series of new dinuclear rare-earth metal alkyl complexes supported by indolyl ligands in novel μ-η²:η¹:η¹ hapticities are synthesized and characterized. Treatment of [RE(CH₂SiMe₃)₃(thf)₂] with 1 equivalent of 3-(tBuNCH)C₈H₅NH (L₁) in THF gives the dinuclear rare-earth metal alkyl complexes trans-[(μ-η²:η¹:η¹-3-{tBuNCH(CH₂SiMe₃)}Ind)RE(thf)(CH₂SiMe₃)]₂ (Ind=indolyl, RE=Y, Dy, or Yb) in good yields. In the process, the indole unit of L₁ is deprotonated by the metal alkyl species and the imino CN group is transferred to the amido group by alkyl CH₂SiMe₃ insertion, affording a new dianionic ligand that bridges two metal alkyl units in μ-η²:η¹:η¹ bonding modes, forming the dinuclear rare-earth metal alkyl complexes. When L₁ is reduced to 3-(tBuNHCH₂)C₈H₅NH (L₂), the reaction of [Yb(CH₂SiMe₃)₃(thf)₂] with 1 equivalent of L₂ in THF, interestingly, generated the trans-[(μ-η²:η¹:η¹-3-{tBuNCH₂}Ind)Yb(thf)(CH₂SiMe₃)]₂ (major) and cis-[(μ-η²:η¹:η¹-3-{tBuNCH₂}Ind)Yb(thf)(CH₂SiMe₃)]₂ (minor) complexes. The catalytic activities of these dinuclear rare-earth metal alkyl complexes for isoprene polymerization were investigated; the yttrium and dysprosium complexes exhibited high catalytic activities and high regio- and stereoselectivities for isoprene 1,4-cis-polymerization.

Under microwave irradiation and solvent-free conditions, rare-earth metal chlorides (RECl₃) have been efficient catalysts for one-pot synthesis of quinoline derivatives to give products in good to excellent yields through the multi-component reactions of aldehydes, amines, and alkynes. The rare-earth metal chlorides can be recycled for six times without notable loss of catalytic activities. This new synthetic approach has prominent features of a short reaction time, high yields of products, operational simplicity, broad substrate scopes, environmentally friendly property and commercially available catalysts. It extends the applications of rare-earth metal compounds as catalysts in organic synthesis.

A straightforward strategy for assembling polymeric dimers from amphiphilic nanoparticles is reported. Amphiphilic polymeric nanoparticles with a mixed-shell of PEO/P2VN blocks and a flexible core of PAA blocks are fabricated by a non-covalent crosslinking method. Uniform polymeric dimers are efficiently and simply obtained via hydrophobic interactions under optimized conditions in selective solvent. The steric hindrance generated by reorganization of hydrophilic polymer brushes during the interparticle association is critical for morphological selectivity in the assembly. General applicability offers the possibility to organize functional NPs into superstructures with well-defined geometry and association numbers.

Reaction of sulfonylated binaphthol [2-hydroxy-2′-tosyloxy-1,1-binaphthyl (1a, Ts-Binol) or 2-hydroxy-2′-(phenylsulfonyloxy)-1,1-binaphthyl (1b, Ps-Binol)] with 1 equiv. of ZnEt₂ afforded zinc complexes [(Ts-Binol)ZnEt]₂ (2a) and [(Ps-Binol)ZnEt]₂ (2b). Further reaction of zinc complexes 2a and 2b with benzyl alcohol (BnOH) gave the zinc benzyloxide [(Ts-Binol)₂Zn₂(OBn)₂]₂ (3a) and [(Ps-Binol)₂Zn₂(OBn)2]₂ (3b). Alternatively, the zinc benzyloxides 3a and 3b could also be obtained by reaction of compound 1a or 1b with Zn(OBn)₂ (in situ reaction of ZnEt₂ and BnOH). The complexes were fully characterized by elemental analyses and spectroscopic analyses, and complexes 2a, 2b and 3a were further characterized by single-crystal X-ray analyses. The catalytic activities of these zinc complexes towards ring-opening polymerization of ε-caprolactone and D,L-lactide were studied.

A series of rare earth metal amido complexes bearing methylene-linked pyrrolyl-amido ligands were prepared through silylamine elimination reactions and displayed high catalytic activities in hydrophosphonylations of aldehydes and unactivated ketones under solvent-free conditions for liquid substrates. Treatment of [(Me₃Si)₂N]₃Ln(μ-Cl)Li(THF)₃ with 2-(2,6-Me₂C₆H₃NHCH₂)C₄H₃NH (1, 1 equiv) in toluene afforded the corresponding trivalent rare earth metal amides of formula {(μ-η⁵:η¹):η¹-2-[(2,6-Me₂C₆H₃)NCH₂](C₄H₃N)LnN(SiMe₃)₂}₂ [Ln=Y (2), Nd (3), Sm (4), Dy (5), Yb (6)] in moderate to good yields. All compounds were fully characterized by spectroscopic methods and elemental analyses. The yttrium complex was also characterized by ¹H NMR spectroscopic analyses. The structures of complexes 2, 3, 4, and 6 were determined by single-crystal X-ray analyses. Study of the catalytic activities of the complexes showed that these rare earth metal amido complexes were excellent catalysts for hydrophosphonylations of aldehydes and unactivated ketones. The catalyzed reactions between diethyl phosphite and aldehydes in the presence of the rare earth metal amido complexes (0.1 mol %) afforded the products in high yields (up to 99 %) at room temperature in short times of 5 to 10 min. Furthermore, the catalytic addition of diethyl phosphite to unactivated ketones also afforded the products in high yields of up to 99 % with employment of low loadings (0.1 to 0.5 mol %) of the rare earth metal amido complexes at room temperature in short times of 20 min. The system works well for a wide range of unactivated aliphatic, aromatic or heteroaromatic ketones, especially for substituted benzophenones, giving the corresponding α-hydroxy diaryl phosphonates in moderate to high yields.

Efficient methods have been developed for the direct synthesis of amides from aldehydes and a straightforward route to propiolamidines using cyclopentadienyl-free rare-earth metal amides [{(CH₂SiMe₂){(2,6-iPr₂C₆H₃)N}₂}Ln{N(SiMe₃)₂}(THF)] [Ln = Yb (1), Y (2), Dy (3), Sm (4), Nd (5)] as versatile catalysts. The results indicate that in the direct synthesis of amides from aldehydes the catalysts have the activity order 2 > 1  3  4  5. These methods have the advantage of easy preparation of the catalysts, low catalyst loading, high conversion of substrates to products, mild reaction conditions, and compatibility with a wide range of substrates.

A series of chiral substituted 5-(pyrrolidin-2-yl)tetrazoles have been synthesized and evaluated as organocatalysts for the asymmetric Biginelli reaction. The relationship between catalytic activity and the different catalyst structures is briefly discussed. By using the optimized catalyst C¹⁰ (10 mol-%), a series of 3,4-dihydropyrimidin-2(1H)-one (DHPM) derivatives have been obtained in 63–88 % yields and 68–81 % ee values within 24 h at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

In the presence of 10 mol% lanthanide amide [(Me₃Si)₂N]₃Ln(µ-Cl)Li(THF)₃, the aza-Henry reaction of N-tosyl imines with nitroalkanes (1:5 molar ratio) could be performed in good yields. The lanthanide amide-catalyzed aza-Henry reaction has the features of mild reaction conditions, tolerance of a variety of aromatic aldehyde-derived imines and nitroalkanes, short time and good chemical yields. A catalytic mechanism for the reaction was also proposed.

This contribution is to report the application of simple lanthanide amides [(Me₃Si)₂N]₃Ln(µ-Cl)Li(THF)₃ exhibiting a high activity toward catalyzing Henry reaction of aromatic aldehydes with nitroalkanes to give β-nitroalcohols or β-nitroolefins with a very good chemoselectivity by controlling the reaction temperatures and by selecting aromatic aldehydes. It was found that this catalytic system was compatible with a wide range of substrates of aldehydes.