Catalytic intramolecular hydroamination of aminoallenes using titanium and tantalum complexes of sterically encumbered chiral sulfonamides
作者:Fanrui Sha、Emily A. Shimizu、Hannah S. Slocumb、Sydney E. Towell、Yi Zhen、Hanna Z. Porter、Michael K. Takase、Adam R. Johnson
DOI:10.1039/d0dt02557g
日期:——
work, four sterically encumbered chiral sulfonamides derived from naturally occurring amino acids were prepared. These compounds undergo protonolysis reactions with Ti(NMe2)4 or Ta(NMe2)5 to give monomeric complexes as determined by both DOSY NMR and X-ray crystallography. The resulting complexes are active for the ring closing hydroamination hepta-4,5-dienylamine to give a mixture of tetrahydropyridine
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.