Science of Synthesis

González-Bello, C.; Castedo, L., Science of Synthesis, (2007) 31, 326.

The Fries rearrangement of phenolic esters provides a useful route to acylphenols.[‌30‌] The reaction requires the use of Brønsted acids (e.g., H3PO4, HF, TsOH, Nafion-H, or MsOH)[‌31‌–‌35‌] or Lewis acids (e.g., AlCl3, BF3, TiCl4, SnCl4, FeCl2, ZnCl2, or mixtures of AlCl3 and ZnCl2 supported on silica gel).[‌36‌,‌37‌] However, aluminum trichloride is the most frequently used catalyst. The acids, especially the Lewis acids, are used in excess because they form complexes with both the starting material and the products. This rearrangement affords a mixture of ortho- and para-substituted acylphenols, the ratio of which depends on the temperature and the reaction medium. Usually, high temperatures favor the ortho-rearrangement products, and the para-derivatives are obtained at lower temperatures. An exception is the zirconium(IV) chloride mediated rearrangement, which affords mainly the ortho-product at room temperature.[‌38‌] For example, treatment of 3-tolyl acetate (‌37‌) with 2 equivalents of aluminum trichloride affords mainly the 4-hydroxyacetophenone ‌39‌ at 25°C and mainly the 2-hydroxyacetophenone ‌38‌ at 160°C (‌Scheme 12‌).[‌39‌,‌40‌] The latter is also the main product obtained using zirconium(IV) chloride at 20°C.[‌38‌]

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‌Meeeeeeeeee 88‌

Mee eeeeeeeeeee eee eeeeeeeee eeeeeeeeee ee eee Meeee eeee eee eeeeeeee eee eeeeeeeeeee ee eeeee eeeeeeeee. Meeeee, eeeee eeeeeeeee eeeeeeee ee eee Meeee eeeeeeeeeeeee eeee eeee eeeeeeee eeeeeeeeeeee eeeee eeeeeee(MMM),[‌88‌,‌88‌] eeeeeeee(MMM),[‌88‌] ee eeeeeee(MM) eeeeeeeeeeeeeeeeeeeeeeeee[‌88‌] eeeeeeeee, ee eeeeeeeeeee ee eee eeeeeeeeee ee eeee eeeeee ‌88‌ eeee eeeeeee ‌88‌ (‌Meeeee 88‌).

‌Meeeee 88‌ Meeeeeeee Meeee Meeeeeeeeeeee ee Meeeeeee Meeeee[‌88‌,‌88‌]

‌Meeeeeeeeee 88‌

e Mee eeeeeeee eee eeeeeee eee ee 88 M MeMeM8 ee MeMM8 ee 88°M.

e Meeeeeee eeee 88 e.

Mee Meeee eeeeeeeeeeeee eee eeee ee eeeeeeee ee e eeeeeee–eeeee eeeeeeee eeeeeee eeeeeeeeee eeeeee (eeeeee eeeee ee eeee eeeeeeeeeee) eee ee eeeeeeeeeeeee eeeeeee (eeee ee MeMe, e-MeMe, ee e-MeMe) ee eeeeeee eeeee. Mee eeeeeeeee eeeeeee eeeeeeeee ee eee ee eeeee eeeeeee eee eeeee eeeeeeeeeeeeeeee eeee eee eeeee eeeee ee eeeeee eee eeeee-eeeeeeeeeeeee eeeeeeee eeeeeeeeeeeeeeee ee eee eeeeeeeeeeee.[‌88‌] Mee eeeeeee, eee eeeeeee 8-eeeeeeeeeee eeeeeee ‌88‌ eee eeeeeeeeeee eeeeeeeeeeeeeeee eeee 8-eeeeeeee eeeeeeeeeee ‌88‌ ee eeeeeeeee eeee eeeeeeeeeeee ee −888°M (‌Meeeee 88‌).[‌88‌]

‌Meeeee 88‌ Meeeeeeeeee ee 8-Meeeeeeeeee Meeeeee eeee 8-Meeeeeee Meeeeeeeeee[‌88‌]

Mee Meeee eeeeeeeeeeeee eee ee eeee eeeeeeee ee eeeeeeeeee. Mee eeeee-Meeee eeeeeeeeeeeee eee eeee eeeee ee eeeeeee ee eeeeeee eeeeeeeee M—M eeee eeeeeeee eeee eee eeeeeee eeeeeee eeeee, ee eeeeeee e eeeeeeee eeeeeee eee ee eeee eeeeeee, eeeeeeee ee eeeeeee eeeeeeeeeeeee.[‌88‌,‌88‌] Me ee eee eeeeeee eeeeee, eee eeeee- eee eeee-eeeeeeeeeeeee eeeeeeee eee eeeeeee eeeeeeee, eee eeeee eeeeeeee eeeee eeeeeeee eeeeeee ee eee eeeeeeee eeeeeeeeee. Mee 8-eeeeeeeeeee eeeeeee eee ee eeeeeeee eeeeeeeeeeeeeeee ee eeeeeeeeee eee eeeeeeeee ee eee eeeeeee, ee ee eeeee eeeeeeeee (eeeee) eeee eeeeeeee eee eeeeeeeeeeeee eeeeeee ee eee eeeeeeee eeee eee eeeeeeeee eeeeee eee eeeeee ee eee eeeeeeee. Meeeeee eeee eeeeeeeee eeeeeee eeeeeeeeeeeee,[‌88‌–‌88‌] eeeeeee eeeeeeeee,[‌88‌,‌88‌] ee eeeeee eeeeeeee.[‌88‌] Mee eeeeeee, eeeeeeeeeee ee eee eeeeee eeeeee ‌88‌, eeeeee ee eeeeeee ee ee eeeeeeee, eeeee e eeeeeee ee eee eeeee-eeeeeeeeeee ‌88‌, eee eeee-eeeeeeeeeee eeeeeee ‌88‌ (‌Meeeee 88‌). Meeeeee, eeeeee eee 8-eeeeeeeeeee ‌88‌ eee eeeeeeee ee eee eeeeeeee ee β-eeeeeeeeeeee.[‌88‌] Meeeeeeeeeee, eeeeee (‌88‌) ee eeeeeeee ee e eeee eeeeeee.

‌Meeeee 88‌ Meeeeeeeeee ee Meeeeeeeeee Meeeeee ee Meeee-Meeee Meeeeeeeeeeee ee Meeeee Meeeeeee[‌88‌,‌88‌]

‌Meeeeeeeeee 88‌

Meeeeeeeeeee Meeeeeeee

Meeeeeeeeee ‌88‌; Meeeeee Meeeeeeee:[‌88‌]

Meeeee M: Me e eeeeeee eeee ee eee eeee eeeee ‌88‌ (8 eeee) ee eeeeeee (8 eM) eee eeeee Me(MMe)8•8M8M (8.88 eeee). Mee eeeeeeeee eeeeeee eee eeeeee ee 888°M eee 8–88 e eee eeee eeeeee ee ee eee M8M eeeee. Meeeeeeeee eeee Me8M, eeeeee (Me8MM8), eeeeeeeeee, eee eeeeeeeeeeeee eeeeeeee e eeeeeee, eeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, MeMMe/eeeeeee 8:88 ee 8:8); eeeee: 88–88%.

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) 8/8e, 888.
• 8.Meeeee-Meee, (8888) 8/8e8, 8888.