A transition-metal-free synthesis of fluorinated naphthols.

Herein, we describe a transition-metal-free protocol for the conversion of simple 2-allyl-3-(trifluoromethyl)phenols into substituted 5-fluoronaphthalen-1-ols. The key events of this reaction include the selective activation of two C-F bonds and formation of an intermediate hexatriene system, which undergoes a 6π electrocyclization, followed by rearomatization. This concept enables the rapid conversion (three steps) of various commercially available 3-(trifluoromethyl)phenols into novel fluorine-containing naphthols, which are difficult to prepare by previous methods. The reported sequence was also extended to a one-pot transformation of 3-(trifluoromethyl)phenols into 5-fluoronaphthalen-1-ols.