Sterically encumbered chiral amino alcohols for titanium-catalyzed asymmetric intramolecular hydroamination of aminoallenes
摘要:
A variety of sterically encumbered amino alcohol ligands were prepared in a two-step modular synthesis. The titanium complexes of these ligands were prepared in situ and used as catalysts for hydroamination. The intramolecular hydroamination of 6-methyl-hepta-4,5-dienylamine at 135 degrees C with 5 mol % catalyst gave exclusively 2-(2-methyl-propenyl)-pyrrolidine with enantiomeric excesses up to 16%. (C) 2009 Elsevier Ltd. All rights reserved.
Asymmetric Catalytic Intramolecular Hydroamination of Aminoallenes by Tantalum Amidoalkoxide Complexes
作者:Michelle C. Hansen、Carolyn A. Heusser、Tarun C. Narayan、Kristine E. Fong、Nagiko Hara、Alexander W. Kohn、Alexander R. Venning、Arnold L. Rheingold、Adam R. Johnson
DOI:10.1021/om200446v
日期:2011.9.12
monomeric with an approximate trigonal-bipyramidal geometry. The resulting complexes were examined for their in situ activity for catalytic asymmetric hydroamination/cyclization of an aminoallene. Enantioselectivities up to 80% ee were observed for the cyclization of 6-methylhepta-4,5-dienylamine to 2-(2-methylpropenyl)pyrrolidine at 135 °C with 5 mol % catalyst loading.
Sterically encumbered chiral amino alcohols for titanium-catalyzed asymmetric intramolecular hydroamination of aminoallenes
作者:Amanda J. Hickman、Lauren D. Hughs、Casey M. Jones、Hanhan Li、Joanne E. Redford、Samuel J. Sobelman、J. Andrew Kouzelos、Adam. R. Johnson
DOI:10.1016/j.tetasy.2009.04.013
日期:2009.6
A variety of sterically encumbered amino alcohol ligands were prepared in a two-step modular synthesis. The titanium complexes of these ligands were prepared in situ and used as catalysts for hydroamination. The intramolecular hydroamination of 6-methyl-hepta-4,5-dienylamine at 135 degrees C with 5 mol % catalyst gave exclusively 2-(2-methyl-propenyl)-pyrrolidine with enantiomeric excesses up to 16%. (C) 2009 Elsevier Ltd. All rights reserved.