Synthetically important ring opening reactions by alkoxybenzenes and alkoxynaphthalenes

Abstract

This concise review reports the ring opening functionalizations of small sized molecular rings with alkoxybenzenes/alkoxynaphthalenes in Friedel–Crafts fashion.

Catalytic production of tetrahydropyran (THP): a biomass-derived, economically competitive solvent with demonstrated use in plastic dissolution

“…THF has a ring strain energy (RSE) of 6.9 kcal mol −1 , but THP has a much lower RSE of 2.0 kcal mol −1 . [40][41][42] Five-membered cyclic ethers such as THF and MeTHF are susceptible to ring-opening polymerization (ROP) to form polyethers as undesired side products, especially in the presence of acidic catalysts or reagents. 43 We hypothesized that six-membered THP would be more resistant to ROP due to its negligible ring strain.…”

Unlocking the Friedel-Crafts arylation of primary aliphatic alcohols and epoxides driven by hexafluoroisopropanol

“…81,82 The reaction was also compatible with aziridines to access phenylethylamine 79 in 97%. 8 Scope of dehydrodiarylation of epoxides Next, we turned our attention to the challenging one-pot dehydrodiarylation of epoxides (Scheme 3). To optimize the formation of 1,1,2-triarylethanes, we studied the reaction of (pentafluorophenyl)ethylene oxide with m-xylene, which would serve as a nucleophile for both steps.…”

“…(1) Ring-opening Friedel-Crafts reactions of terminal epoxides, which give branched products, are mainly limited to electron-rich styrene oxides and arenes when Lewis or Brønsted acid promoters are employed (Scheme 1). [7][8][9] Consequently, epoxide arylation strategies based on transition metal catalysis or photocatalysis have been developed but suffer from poor access to branched products, [10][11][12][13][14][15][16] notably for alkyl epoxides. 11 For styrene oxides, more branch-selective arylation examples are known, 14,15 but those bearing strong electron-withdrawing groups remain inaccessible.…”

Theoretical Study on the Origin of Abnormal Regioselectivity in Ring-Opening Reaction of Hexafluoropropylene Oxide

“…Epoxides play an essential role in the fields of pharmaceuticals [ 1 ], materials [ 2 , 3 ], and organic syntheses [ 4 , 5 , 6 , 7 , 8 ] owing to their unique biological and chemical activities. Due to the large ring strain of epoxides compared to linear aliphatic ethers, the epoxide carbon atoms can be attacked by nucleophiles to release the ring strain [ 9 ].…”