Total Synthesis of (+)-Oxo-tomaymycin

(+)-Oxo-tomaymycin, a naturally occurring substance of the pyrrolo-1,4-benzodiazepine family, was synthesized using a short and efficient route. The key construction of the seven-membered ring by amide bond formation was realized via a chemoselective Ar-NO2 reduction using TiCl3 under acidic conditions, followed by a spontaneous cyclization. This synthesis was easily scaled up to 80 g, and it should be amenable to the production of larger quantities.