Novel approach to bis(indolyl)methanes: de novo synthesis of 1-hydroxyiminomethyl derivatives with anti-cancer properties.

A versatile and broad range approach to previously unknown bis(indolyl)methane oximes based on two consecutive hetero Diels-Alder cycloaddition reactions of electrophilic conjugated nitrosoalkenes with indoles is disclosed. The cytotoxic properties and selectivity of some adducts against several human cancer cell lines pointing to a promising role in the development of anti-tumoural drugs, in particular for leukaemia and lymphoma.