Cyclic intermediates of the formula (XXXIV), where R1 is an aryl group such as an optionally substituted phenyl group, can be formed by Friedel Crafts alkylation of an aryl compound R1???H with a compound of the formula (XXXV): The alkylation is typically carried out in the presence of a Lewis acid such as aluminium chloride at a reduced temperature, for example less than 5?? C.The Friedel Crafts