Synthesis of (hetero)biaryl compounds has become one of the most important methodologies in organic synthesis due to the abundance of the biaryl structural motif in biologically active molecules, in natural products and in materials chemistry. However most of the current synthetic methods rely on the use of transition metal catalyst, sometimes with toxic ligands, and heating. Additionally, both reacting units must be pre-activated as, for instance, boronic acids, zincates, halides, stannanes, triflates, etc. Thus in general, synthesis of biaryl compounds has a negative impact in the environment, besides the high economic cost of the reagents and procedures employed. We have recently reporteda metal-free direct C-H arylation of (hetero)arenes with anilines, promoted by catalytic amounts of ascorbic acid (vitamin C), with no heating or irradiation required. Starting from an aniline, the corresponding arenediazonium ion is generated in situ and immediately reduced by vitamin C to an aryl radical that undergoes a homolytic aromatic substitution with a (hetero)arene. This synthetic procedure is mild, operationally simple, and constitutes a greener approach to arylation. Indeed, ascorbic acid and its decomposition product, dehydroascorbic acid, are completely non-toxic. Other residues of this reaction are equally non-toxic, such as water, nitrogen or tert-butanol. Additionally, this methodology is energy-efficient because it requires neither heating nor irradiation.

Trabajo presentado en la XXV Reunión Bienal de Química Orgánica celebrada en Alicante del 4 al 6 de junio de 2014.

Peer Reviewed