合成路线1

Nitration of 2-biphenylcarboxylic acid (I) with fuming nitric acid produced a mixture of two regioisomeric dinitro derivatives. Subsequent refluxing of this mixture in dimethylacetamide provided, after crystallization, the required benzocoumarin (II). Catalytic hydrogenation of the nitro group of (II) over Pd/C yielded amine (III). Then, heating of amine (III) with acetone in a sealed tube in the presence of iodine furnished the coumarinoquinoline (IV). The reaction of (IV) with 3-fluorobenzylmagnesium bromide (V) gave the intermediate cyclic hemiacetal (VI), which was finally dehydrated with p-toluenesulfonic acid in CH2Cl2 to afford the title benzylidene compound.