prov:value
| - he meaning indicated above, and [0121] X1 represents a leaving group, preferably mesylate, tosylate or halogen, particularly preferably bromine or iodine, [0122] to give compounds of the general formula (Ia), [0123] in which [0124] R1, R2, R3, R4 and E have the meaning indicated above, [0125] in inert solvents, these include halogenohydrocarbons such as methylene chloride, trichloromethane, tetrac
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