The synthesis of benzoannulated indolizidines and quinolizidines
is described through a telescoping reaction sequence featuring hydroaminoalkylation
and nickel-catalyzed C–N bond coupling. An in situ generated tantalum (V) ureate catalyst is used to form new Csp3Csp3 bonds between saturated N-heterocycles and ortho-chlorostyrene enabled by
the α CH bond activation of the amine. The addition
of a nickel CN coupling catalyst generated from Ni(COD)2 and DPPF to the reaction mixture allowed for cyclization.
Our method leverages the regiodivergent branched and linear products
accessed from N-heterocycle and styrene combinations,
which are uniquely achieved by our tantalum catalyst to produce new N-heterocycle framework derivatives. Total isolated overall
yields of up to 86% were achieved in a single pot. These advances
highlight alternative bond disconnections that enable direct access
to distinct new N-heterocycle derivatives through
early transition metal catalyzed hydroaminoalkylation.