929050-90-8Relevant academic research and scientific papers
Synthesis and application of the first planar chiral strong bronsted acid organocatalysts
Enders, Dieter,Ludwig, Monika,Raabe, Gerhard
, p. 215 - 222 (2012)
The synthesis of planar chiral strong Bronsted acid organocatalysts derived from [2.2]paracyclophane is described. Resolution was accomplished according to a modified protocol involving pseudo-ortho-substituted [2.2]paracyclophane-based sulfoxides for the synthesis of three new sulfonic acids. The first planar chiral phosphoric acid diester was obtained from the corresponding phenyl-substituted diol derived from enantiopure 4-bromo-12-hydroxy [2.2]paracyclophane. These new classes of catalysts were tested in an enantioselective Friedel-Crafts reaction as well as in a direct asymmetric Mannich reaction and gave yields of up to 93% and ee-values of up to 38%. Copyright
Chiral sulfonimide as a bronsted acid organocatalyst for asymmetric Friedel-Crafts alkylation of indoles with imines
Chen, Ling-Yan,He, Hao,Chan, Wing-Hong,Lee, Albert W. M.
experimental part, p. 7141 - 7147 (2011/10/09)
Binaphthyl-based chiral sulfonimide (CSI) is demonstrated for the first time to be an efficient, strong Bronsted acid in asymmetric organocatalysis. A series of CSIs were synthesized and screened in the asymmetric Friedel-Crafts alkylation of indoles with imines. Good to excellent yields and enantioselectivities have been achieved. It was proved that it was crucial to wash the CSI catalyst with HCl before use.
