| http://www.w3.org/ns/prov#value | - In one aspect of the invention, a compound of formula (IIB) wherein L is a halogen atom may be prepared by reaction of a compound of formula (IX): R2???OG (IX) wherein R2 is as hereinbefore defined for a compound of formula (I) and OG 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.
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