Isoxazole as a nitrile synthon: en routes to the ortho -alkenylated isoxazole and benzonitrile with allyl sulfone catalyzed by Ru(II).

A Ru(II) catalyzed regioselective Heck-type C-H olefination of isoxazole with unactivated allyl phenyl sulfone is revealed. The solvent DCM offers dual sp 2 -sp 2 C-H activation via an N -directed strategy, leading to ortho -olefinated isoxazoles with exclusive E -selectivity. On the other hand, in DCE solvent, isoxazole serves as the nitrile synthon and leads to o -olefinated benzonitrile. At a higher temperature (110 °C) in DCE, after the ortho -olefination Ru(II) mediated cleavage of isoxazoles delivered the nitrile functionality.