Cooperative Bi(III)/Co(II) and Bi(III)/Mn(II) heterogeneous catalysts have been developed
enabling efficient oxidative annulations for preparing both cross-coupled imines and
benzimidazoles under ambient conditions in an atom-economic and time-efficient manner,
involving ambient air as oxidant and without the need of any other additives. This
is the first synergistic Lewis acid/transition metal catalyzed annulation which is
potentiated by the interfaces between the building blocks of the catalysts. To achieve
our goals, a useful fabrication process has been developed to heterogenize the transition
metal ions via strong interactions on well-known Sillèn-type bismuth subcarbonate
(bismutite). Their reusability, activity and selectivity as well as water-tolerance
have made them potential competitors to effective heterogeneous/homogeneous catalysts
reported previously.
