Studies Towards the Synthesis of Chrysen-6-ol and Benzo[c]phenanthren-5-ol Derivatives: Usual and Unusual Observations

Abstract

Some interesting observations have been observed in the synthetic studies of chrysen-6-ol and benzo[c]phenanthren-5-ol derivatives by intramolecular cyclization of (2-phenylnaphthalen-1-yl)acetic acid derivatives (4) and (1-phenylnaphthalen-2-yl)acetic acid derivatives (13) with PPA or trifluoroacetic acid (TFA) - trifluoroacetic anhydride (TFAA) mixture. Though chrysen-6-ol derivatives were obtained in very good yields (usual observation) under identical condition attempted cyclization of (1-phenylnaphthalen-2-yl)-acetic acid derivatives (13) produced no benzo[c]phenanthrene-5-ol derivatives (17). On the contrary dimeric intermolecular condensation product (18) (unusual observation) was formed in general in very good to excellent yields. The required precursors (4) were obtained from (2-bromonaphthalen-1-yl)acetonitrile derivative and suitable phenyl boronic acid in two steps although the precursors (13) were prepared from suitable 1-bromo-2-naphthyladehyde and phenyl boronic acid derivatives in six steps.

Key Words:

• benzo[c]phenanthren-5-ol
• chrysen-6-ol
• dimeric product
• polycyclic aromatic hydrocarbon
• PPA or TFA-TFAA cyclization
• synthesis

Acknowledgments

Financial help from CSIR and DST acknowledged gratefully. We are thankful to CSIR for providing NET fellowship to one of the authors (KS).