The starting product dibenzo[a,d]cyclohepta-1,4,6-triene-5-one (I) is prepared by condensation of phthalic anhydride (X) with phenylacetic acid (XI) by means of sodium acetate at 240 C that gives benzalphthalide (XII). This compound is reduced with red phosphorus in refluxing aqueous HI yielding 2-(2-phenylethyl)benzoic acid (XIII), which is then cyclized with polyphosphoric acid at 175 C afforing dibenzo[a,d]cyclohepta-1,4-diene-5-one (XIV). The ketone (XIV) is brominated with NBS in CCl4 to the bromo ketone (XV) and finally dehydrobrominated with triethylamine.
The Grignard reaction of dibenzo[a,d]cyclohepta-1,4,6-triene-5-one (I) with dimethylaminopropyl magnesium (C) chloride in ethyl ether gives 5-hydroxy-5-(3-dimethylaminopropyl)dibenzo[a,d]cyclohepta-1,4,6-triene (IV), which is then treated with HCl in refluxing acetic acid. Alternatively, it can also be obtained by methylation of 5-(3-methylaminopropylidene)dibenzo[a,d]cyclohepta-1,4,6-triene (IX) with formic acid and formaldehyde at 100 C.
The Grignard reaction of dibenzo[a,d]cyclohepta-1,4,6-triene-5-one (I) with allyl magnesium bromide (A) in ethyl ether gives 5-hydroxy-5-allyldibenzo[a,d]cyclohepta-1,4,6-triene (II), which is dehydrated with acetic anhydride and acetyl chloride at 90 C yielding 5-propenylidenedibenzo[a,d]cyclohepta-1,4,6-triene (III). Finally, this compound is treated with phenylmagnesium bromide and dimethylamine (B) at 80 C.
The Grignard reaction of dibenzo[a,d]cyclohepta-1,4,6-triene-5-one (I) with cyclopropyl magnesium bromide (D) in THF gives 5-hydroxy-5-cyclopropyldibenzo[a,d]cyclohepta-1,4,6-triene (V), which is then treated with HBr in acetic acid to yield 5-(3-bromopropylidene)dibenzo[a,d]cyclohepta-1,4,6-triene (VI). Finally, (VI) is treated with dimethylamine (B) in benzene at 95 C. The hydroxycompound (V), obtained as before, is treated with HClO4 in dioxane to yield 5-(3-hydroxypropylidene)dibenzo[a,d]cyclohepta-1,4,6-triene (VII), which is then treated with p-toluenesulfonyl chloride in pyridine to afford the tosyl derivate (VIII). Finally, (VIII) is treated with dimethylamine (B) in benzene at 100 C.