Bardhan-Sengupta phenanthrene synthesis

What is Bardhan-Sengupta phenanthrene synthesis?

The Bardhan-Sengupta phenanthrene synthesis involves a two-step process. Initially, a hydroxy-substituted phenyl alkane or a phenyl-substituted alkene reacts with a phosphorus-containing acid or a dehydrating agent, such as H3PO4, P2O5, or polyphosphoric acid (PPA), to produce a carbocationic species (see list of acronyms).

Bardhan-Senguph phenanthrene synthesis - general reaction scheme
Bardhan-Sengupta phenanthrene synthesis

This intermediate undergoes electrophilic aromatic substitution (SEAr) and proton elimination, resulting in the formation of the corresponding octahydrophenanthrene. Subsequently, the octahydrophenanthrene undergoes dehydrogenation, which yields the final product: the phenanthrene ring system.