Abstract: The synthesis of 4-hydroxy-3-phenylcoumarin 3a from phenol1
and diethylphenylmalonate 2 yields the isocoumarin derivative 4
as a byproduct (1-2%). If 3a is heated with 2 or diphenylcarbonate 6
at 300oC the coumarino-isocoumarin 4 is formed
in 83% or 85% yield, respectively.
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