Efficient One‐Pot Friedel–Crafts Acylation of Benzene and its Derivatives with Unprotected Aminocarboxylic Acids in Polyphosphoric Acid

An expedient route to heterocycles through α-arylation of ketones and arylamides by microwave induced thermal SRN1 reactions

“…Products 3a-k, 3m, 9a-c, 12, 14, and 15 are known compounds and present spectral data as shown in the literature, in agreement with the proposed structures. 1,2-Diphenylethanone (3a), 29 4-(2-oxo-2phenylethyl)benzonitrile (3b), 30 2-(4-methoxyphenyl)-1-phenylethanone (3c), 31 2-(4-uorophenyl)-1-phenylethanone (3d), 31 2-(4-nitrophenyl)-1-phenylethanone (3e), 32 2-(naphthalen-1-yl)-1-phenylethanone (3f), 33 2-(naphthalen-2-yl)-1-phenylethanone (3h), 34 1-phenyl-2-(pyridin-2-yl)ethanone (3i), 35 1-(4-methylphenyl)-2-phenylethanone (3j), 36 1-(4-aminophenyl)-2-phenylethanone (3k), 37 1-(4-chlorophenyl)-2-phenylethanone (3m), 36 1-(allyloxy)-2-iodobenzene (5), 16 2-(2-iodophenyl)-1-phenylethanone (9a), 21 2-(2-bromophenyl)-1-phenylethanone (9b), 38 2-(4iodophenyl)-1-phenylethanone (9c), 21 2-phenylcyclohexanone (12), 39 1-methyl-3-phenylindolin-2-one ( 14), 28 and 2-phenyl-1Hindole (15). 32 3-(2,3-Dihydrobenzofuran-3-yl)-1-phenylpropan-1-one (6) Following the general procedure, using tBuOK (179 mg, 0.75 mmol), acetophenone (0.75 mmol), and aryl halide 5 (0.25 mmol), microwave irradiation at 60 C for 10 min and then purication by radial chromatography (petroleum/ethyl ether, 8/2) provided 6 as light yellow crystals (18 mg, 29% yield).…”

Regioselective acylation of β-enaminones of homoveratrylamine

“…The Friedel-Crafts acylation of activated benzene rings in the presence of polyphosphoric acid (PPA) is a very convenient method for direct synthesis of aromatic ketones. [12][13][14] In our previous reports we have shown that…”

Silica-Supported Polyphosphoric Acid in the Synthesis of 4-Substituted Tetrahydroisoquinoline Derivatives

“…Polyphosphoric acid is a strong mineral acid which has powerful dehydrating properties and is widely used for intramolecular and intermolecular acylations, heterocyclic synthesis, and acid-catalyzed reactions. For instance, in recent reports the cyclization reactions of N , N '-bis(oxotrifluoroalkenyl)-1,3-phenylenediamines in PPA medium [ 43 ], the acylation of benzene and its derivatives with 2-, 3-, 4-aminobenzoic and 4-aminophenylacetic acid in PPA to aminobenzophenones [ 44 ], and the reaction of tryptamine with carboxylic acid in PPA to afford 1-substitued-3,4-dihydro-9 H -β-carboline derivatives [ 45 ], etc , were described. However, the use of PPA has several drawbacks: since 10- to 50-fold excess is generally employed, it is difficult to pour and stir at room temperature, and it is necessary to carefully neutralize the reaction mixtures before the product extraction.…”