Studies on the Alkylation and Chlorination of Fluorenes: Preparation of 9-(2-Hydroxyethyl)fluorene and 2,7-Dichloro-9-(2-hydroxyethyl)fluorene

Efficient large-scale syntheses of 9-(2-hydroxyethyl)fluorene (1) and its 2,7-dichloro derivative 2 are described. Major differences exist in the reactivity of fluorene and its 2,7-dichloro derivative toward 9-alkylation. These differences are attributed to the difference in acidity of the protons in the 9-position of these compounds. Also 2,7-dichlorination of fluorene and its derivatives was satisfactorily achieved by treatment with NCS and conc. HCl in acetonitrile under carefully controlled conditions. Specifically, a highly concentrated solution of substrates and elevated temperatures were required for facile 2,7-dichlorination.