Novel Friedel-Crafts Alkylation of Estrogens in the Presence of Anhydrous FeCl₃ or FeCl₃–Graphite as Catalyst

Summary.

 The introduction of a tert-butyl group at position 2 of the A ring of estrogens leads to enhanced antioxidant effects. Therefore, a generally applicable and convenient method was developed using FeCl₃–graphite or anhydrous FeCl₃ as catalysts in the Friedel-Crafts alkylation of estrogens. The rates and yields of the alkylations were lower with FeCl₃–graphite than with anhydrous FeCl₃, but the regioselectivity of the former were higher. Both catalysts proved to be more effective than typical AlCl₃.