A Disulfonimide Catalyst for Highly Enantioselective Mukaiyama–Mannich Reaction

A new BINOL-derived
chiral disulfonimide has been developed by
introducing 4-methyl-3,5-dinitrophenyl substituents at its 3- and
3′-positions. This chiral disulfonimide catalyst displays high
catalytic efficacy toward the asymmetric Mukaiyama–Mannich
reaction of imines with ketene silyl acetals leading to β-amino
acid esters in good yields (up to 99%) with high diastereoselectivities
(syn/anti up to 97:3) and enantioselectivities
(up to 98% ee). The long-standing problem of the chiral phosphoric
acid-catalyzed asymmetric Mukaiyama–Mannich reaction that requires
a 2-hydroxyphenyl moiety was solved by this disulfonimide catalyst.