Generation of ortho-SF5-Benzyne and Its Diels–Alder Reactions with Furans: Synthesis of 1-SF5-Naphthalene, Its Derivatives, and 1,6(1,7)-Bis-SF5-naphthalenes

Abstract

Generation of ortho-SF5-benzyne was achieved by a lithiation/elimination sequence starting from 2-fluoro-SF5-benzene. The highly reactive ortho-SF5-benzyne intermediate was trapped by furan or 2-methylfuran in situ, and the obtained stable Diels-Alder adducts were subjected to the series of further chemical transformation, which led to the formation of previously unknown 1-SF5-naphthalene and its derivatives with bromo, amino, hydroxy, and methyl substituents, including bis-SF5-substituted naphthalenes. NMR spectroscopy experiments revealed characteristic through-space coupling between the SF5-group's equatorial fluorines and proton/carbon nuclei of -H, -CH3, and -OH substituents in the peri-position to the SF5-group of 1-SF5-naphthalenes.