A highly enantioselective alkoxylation reaction of 3-bromo-3-substituted 2-oxindoles
with alcohols was achieved by a chiral Ni(II)/N,N′-dioxide complex. This strategy provided an efficient route to various enantioenriched
3-alkyl 3-alkyloxy-2-oxindoles with good yield and enantiomeric ratio (40 examples,
up to 99% yield, 95:5 er). Moreover, phenol and benzenethiol were also compatible
with the reaction conditions. The gram-scale synthesis of an optically active product
and its further transformation into CPC-1 analogue demonstrated the potential utility
of the method. In addition, a catalytic cycle as well as a possible working mode was
provided to understand the enantioselectivity of the reaction.
Key words
asymmetric synthesis - alkoxylation - 3-substituted oxindoles - chiral
N,
N′-dioxide - nickel
