H-Bonding Organocatalysed Friedel-Crafts Alkylation of Aromatic and Heteroaromatic Systems with Nitroolefins

Abstract

Catalytic amounts (10 mol%) of bis-arylureas and -thioureas promote the Friedel-Crafts alkylation with nitroolefins of aromatic and heteroaromatic N-containing derivatives. A sizeable improvement of the yields is noticed on running the reactions in the absence of solvent. When applied to indoles this protocol provides in good to excellent yields and with high selectivity the corresponding Michael adducts. Alkylation at position 2 of the 3-methylindole can be achieved combining solvent-free reaction conditions with microwave (MW) irradiation.