Benzomalvin D, a new 1,4-benzodiazepine atropisomer

A new compound, benzomalvin D [5], isolated from a fungal culture of Penicillium sp., is an atropisomer of the previously reported benzomalvin A [1] . Benzomalvins A [1] and D [5] interconvert to form a 4:1 mixture at room temperature and are totally separable by hplc. This equilibrium phenomenon was further explored through total synthesis of benzomalvin A [1] and related compounds, leading to the first report of natural atropisomers of 1,4-benzodiazepines.