prov:value
| - wherein R2 and X are as hereinbefore defined, and X is preferably bromo, preferably in the presence of a base, for example an alkali metal hydride, e.g. sodium hydride, an alkali metal hydroxide or carbonate, e.g. sodium hydroxide or carbonate, or an amine, preferably a tertiary amine, e.g. triethylamine or pyridine, optionally in an inert solvent, for example dichloromethane, dimethylformamide, o
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