Ecofriendly Solvent‐Free Microwave Enhanced Thermal Fries Rearrangement of Anilides and Phenyl Ureas.

Abstract

Rearrangements Rearrangements O 0140Ecofriendly Solvent-Free Microwave Enhanced Thermal Fries Rearrangement of Anilides and Phenyl Ureas. -Fries rearrangement of anilides and phenylureas under microwave irradiation in the presence of an appropriate Lewis acid adsorbed on an inert solid support provides selectively p-aminoaryl ketones [cf. (II), (IV)] or p-aminoaryl amides (VI), resp., in excellent yields within 3 to 5 minutes. -(EASWARAMURTHY, M.; RAVIKUMAR, R.; LAKSHMANAN, A. J.; RAJU*, G. J.; Indian J. Chem., Sect. B: Org. Chem. Incl. Med. Chem. 44 (2005) 3, 635-637; Dep. Chem., Gov. Arts Coll., Ooty, Tamil Nadu, India; Eng.) -A. Forchert 28-041

Direct synthesis of arenecarboxamides through Friedel–Crafts acylation using ureas

“…The urea carbonyl group is minimally electrophilic 5 and if the urea is unsymmetrical there is a chemoselectivity issue. Reports involving the direct conversion of ureas to aromatic carboxamides include: (1) a process based on the Fries rearrangement of N-phenyl ureas, 6 (2) C-aminoacylation of phenoxides using a magnesium/aluminum oxide catalyst at 230 °C 7 , (3) intramolecular cyclization of in situ generated (carbodiimide + acylurea) acylguanidines, 8 (4) intramolecular reactions using N-2-pyridylureas using POCl 3 /PPTS at 138 °C, 9 (5) intramolecular cyclization of an N-phenyl urea at 270-280 °C, 10 (6) cyclization of N-pyrroloureas at 260-280 ° 11 , and (7) a four-membered ring “diisocyanate” undergoing an intramolecular reaction. 12 In addition several papers that involve the aminoacylation of aryllithiums have also been reported.…”

Applications of Zirconium (IV) Compounds in Organic Synthesis

“…As can be seen from the examples presented in Table 1, in most cases a single product was given in good yield and ides by Fries rearrangement of anilides and phenyl ureas in solvent-free conditions under microwave irradiation (Scheme 56) [114]. Scheme 56.…”

Applications of bismuth(iii) compounds in organic synthesis

“…314 Raju and co-workers have reported that BiCl 3 promotes the microwave enhanced thermal Fries rearrangement of anilides and phenyl ureas to yield aminosubstituted aryl ketones. 315…”