428819-08-3Relevant academic research and scientific papers
Use of group 4 Bis(sulfonamido) complexes in the intramolecular hydroamination of alkynes and allenes
Ackermann, Lutz,Bergman, Robert G.,Loy, Rebecca N.
, p. 11956 - 11963 (2007/10/03)
Titanium tetrakis(amido) complexes catalyze the intramolecular hydroamination of alkynes and allenes more efficiently than Cp-based species. We report here that electron-withdrawing and sterically demanding bis(sulfonamido) ligands lead to enhanced catalytic activity. Zirconium analogues have also been prepared, and the tosyl-substituted complex 20 has been structurally characterized. As in the titanium series, bis(sulfonamido) zirconium catalysts are more efficient in the intramolecular hydroamination of allenes than bis(cyclopentadienyl) complex Cp2ZrMe2 (23). Furthermore, these compounds transform 1,3-disubstituted aminoallenes with high stereoselectivity to the Z-allylamines and allow the hydroamination of a trisubstituted allene. Titanium bis(sulfonamido) imido complex 27 was synthesized. It converts aminoallene 10 to cylic imine 11 with a rate comparable to that of tetrakis(amide) 15, supporting the hypothesis of a catalytically active titanium imido intermediate.
A highly reactive titanium precatalyst for intramolecular hydroamination reactions.
Ackermann, Lutz,Bergman, Robert G
, p. 1475 - 1478 (2007/10/03)
[reaction: see text]. Tetrakisamido titanium complexes are significantly more active than Cp2TiMe2 (1) in the intramolecular hydroamination of aminoalkynes and aminoallenes. In the latter case, the regioselectivity of the transformation depends on the nature of the precatalyst, yielding the most selective and reactive catalysis with the bis(sulfonamido) complex 11.
