Catalytic Addition of Nitroalkanes to Unactivated Alkenes via Directed Carbopalladation

We report a redox-neutral catalytic coupling of nitroalkanes
and
unactivated alkenes that proceeds by a directed carbopalladation mechanism.
The reaction is uniquely enabled by the combination of PdI2 as the precatalyst and HFIP solvent. Structurally complex nitroalkane
products, including nitro-containing carbo- and heterocycles, are
prepared under operationally convenient conditions without the need
for toxic or corrosive reagents. Deuterium labeling experiments and
isolation of a catalytically relevant intermediate shed light on the
reaction mechanism. By taking advantage of different catalytic activation
modes, we demonstrate orthogonal methods for site-selective functionalization
of a polyfunctional nitroalkyl ketone. Density functional theory (DFT)
calculations show that the carbopalladation transition state is stabilized
by a Na···I interaction and H···I hydrogen
bond with HFIP.