New Highly Active Heteroscorpionate-Containing Lutetium Catalysts for the Hydroamination of Aminoalkenes: Isolation and Structural Characterization of a Dipyrrolidinide鈥揕utetium Complex
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- 作者：Antonio Otero ; Agust铆n Lara-S谩nchez ; Carmen N谩jera ; Juan Fern谩ndez-Baeza ; Isabel M谩rquez-Segovia ; Jos茅 Antonio Castro-Osma ; Javier Mart铆nez ; Luis F. S谩nchez-Barba ; Ana M. Rodr铆guez
- 刊名：Organometallics
- 出版年：2012
- 出版时间：March 26, 2012
- 年：2012
- 卷：31
- 期：6
- 页码：2244-2255
- 全文大小：602K
- 年卷期：v.31,no.6(March 26, 2012)
- ISSN：1520-6041
文摘
The reactions of the hybrid scorpionate/cyclopentadiene compounds, as a mixture of regioisomers鈥?-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethyl]-1,3-cyclopentadiene and 2-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethyl]-1,3-cyclopentadiene (bpzcpH) and 1-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1-tert-butylethyl]-1,3-cyclopentadiene and 2-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1-tert-butylethyl]-1,3-cyclopentadiene (bpztcpH)鈥攚ith [Lu(CH2SiMe3)3(thf)2] proceed in very high yields to give the free solvent neutral heteroscorpionate dialkyl lutetium complexes [Lu(CH2SiMe3)2(bpzcp)] (1) and chiral [Lu(CH2SiMe3)2(bpztcp)] (2). The structures in solution of 1 and 2 were investigated by VT NMR spectroscopy, and a fluxional behavior corresponding to an exchange between the alkyl groups was observed. The lutetium complex [Lu(CH2SiMe3)2(bpztcp)(thf)] (3) was isolated as an enantiomerically enriched complex. Supramolecular CH鈭捪€ interactions between molecules in crystals of 3 have been identified in its X-ray molecular analysis, and they explain the formation of a conglomerate among molecules of 3. Complexes 1鈥?b>3 are efficient catalysts for the intramolecular hydroamination of aminoalkenes, giving TOF values of up to 475 h鈥? at 90 掳C for 2,2-diphenyl-pent-4-enylamine (4) by using complex 3 as catalyst. Enantioselectivities up tp 70% ee were achieved in the cyclization of the 1,2-disubstituted olefin 6 with the high enantiopurity complex 3. The hydroamination reactions show apparently zero-order rate dependence on substrate concentration and first-order rate dependence on catalyst concentration. Additionally, bicyclization of 2-allyl-2-methylpent-4-enylamine (10) was achieved at 60 and 100 掳C, giving exo,exo-2,4,6-trimethyl-1-azabicyclo[2.2.1]heptane (12). The protonolysis reaction of complex [Lu(CH2SiMe3)2(bpztcp)] (2) with 2 equiv of 2,2-diphenyl-pent-4-enylamine (4) yielded a dipyrrolidinide lutetium complex [Lu(NC4H5-2-Me-4,4-Ph2)2(bpztcp)] (13) as a mixture of two diastereoisomers. The structures of the complexes were determined by spectroscopic methods, and the X-ray crystal structures of 3 and 13 were also established.