Patent attributes
A spirofluorenol such as 3′,9′-dimethoxy-5′-hydroxyspiro[(1H-cyclopent[d,e,f]phenanthrene)-1,7′-benzo[c]fluorene] is produced by protecting a hydroxyl group bonded to a particular fluorenone compound such as 3,9-dimethoxy-5-hydroxybenzo[c]fluorene-7-one with “a substituted silyl group in which the sum of carbon atoms of substituents bonded to a silicon atom is 5 to 12”, such as a t-butyldimethylsilyl group, then, reacting the fluorenone compound with a particular organometal compound such as 1-lithiophenanthrene so as to be transformed into a spiro form and, then, removing the protection therefrom. This method makes it possible to efficiently produce the spirofluorenol which is useful as a starting material for producing photochromic compounds.
