Boron-containing enamine and enamide linchpins in the synthesis of nitrogen heterocycles

J Am Chem Soc. 2014 Dec 17;136(50):17669-73. doi: 10.1021/ja510963k. Epub 2014 Dec 5.

Abstract

The use of α-boryl enamine and enamide linchpins in the synthesis of nitrogen heterocycles has been demonstrated. Boryl enamines provide ready access to the corresponding α-halo aldehydes, which undergo regioselective annulation to form borylated thiazoles. A condensation/amidation sequence converts α-boryl aldehydes into stable α-boryl enamides without concomitant C → N migration. We also show that palladium-catalyzed cyclization of α-boryl enamides leads to synthetically versatile isoindolones. These molecules can be subsequently used to access polycyclic scaffolds.