is a leaving group, for example an alkanesulphonate group such as a methanesulphonate group, with an anhydrous alkali metal halide such as anhydrous lithium bromide.For example, a compound of formula (IX) and a suitable halogenating agent, for example anhydrous lithium bromide, in a suitable solvent, for example, acetone, are refluxed with stirring for a suitable period of time, for example 3 hour