Alternatively, ketones of formula (6) may be prepared by reaction of a halide of formula (8): ##STR9## where Hal is a halogen atom such as a bromine or chlorine atom! by halogen-metal exchange with a base such as n-butyllithium followed by reaction with a nitrile R4 CN, an acid chloride R4 COCl or an ester R4 CO2 Alk (where Alk is an alkyl group, e.g. a methyl group), in a solvent such as tetrahyd