Metal-Free Air Oxidation in a Convenient Cascade Approach for the Access to Isoquinoline-1,3,4(2H)-triones

Herein we describe a very useful application of the readily available trifunctional aromatic ketone methyl-2-(2-bromoacetyl)benzoate in reactions with primary amines. An unexpected in situ air oxidation that follows a cascade process allowed the access to a series of isoquinoline-1,3,4(2H)-triones, a class of heterocyclic compounds of great interest containing an oxygen-rich heterocyclic scaffold. A modification of the original protocol, utilizing a Staudinger reaction in the presence of trimethylphosphine, was necessary for the synthesis of Caspase inhibitor trione with free NH group.