Facile One-Pot Syntheses of Amidines and Enamines from Oximes via Beckmann Rearrangement Using Trifluoromethanesulfonic Anhydride

Abstract

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Iodine-Mediated Synthesis of 3H-Indoles via Intramolecular Cyclization of Enamines

“…1 H NMR (ppm) δ 10.69(s, 1H), 7.28-7.24(m, 3H), 7.20-7.18(m, 2H), 7.05(d, J = 7.2Hz, 1H), 6.75(dd, J = 7.6, 7.2Hz, 1H), 6.69(dd, J = 7.2, 7.2Hz, 1H), 6.24(d, J = 7.6Hz, 1H), 4.25(q, J = 7.2Hz, 2H), 2.38(s, 3H), 1.72(s, 3H), 1.34(t, J = 7.2Hz, 3H); 13 Diethyl 2-(phenyl(phenylamino)methylene)malonate (1j). Following a modified procedure by Teruaki Mukaiyama, [6] to a solution of benzophenone oxime (0.5 mmol) and triethylamine (0.50 mmol) in toluene (6.0 mL) was added a trifluoromethanesulfonic anhydride (0.75 mmol) under a nitrogen atmosphere at -78 °C. After stirring for 5 min, 3.0 equivalents of sodium enolate of diethyl malonate dissolved in tetrahydrofuran were added and the reaction mixture was slowly warmed up to room temperature.…”

A practical synthesis of 3-chloro-2,4-difluoro-5-hydroxybenzoic acid

“…Amino hydrolysis of an aryl amine can be used for preparing phenols. [13][14][15][16] As shown in Scheme 3, the retrosynthetic analysis suggests that compound 1 can be synthesized by the hydrolysis of diazonium salt 8, which is the typical method for introducing a hydroxy group into an aromatic ring. Compound 8 could be obtained by the diazotization of compound 9, which occurs rapidly in concentrated sulfuric acid.…”

Amine‐Free Approach toward N‐Toluenesulfonyl Amidine Construction: A Phosphite‐Mediated Beckmann‐Like Coupling of Oximes and p‐Toluenesulfonyl Azide

“…Despite the fact that the Beckmann rearrangement is highly useful for constructing amides,9 the analogous approach toward amidines by trapping the intermediate nitrilium with a primary amine was found to proceed at best in poor yield 10. Given our recent work on phosphorus‐mediated CN bond construction,11 we envisioned a solution to this challenge in amidine construction which involves the coupling of the oxime 1 and TsN 3 to yield the amidine 3 via iminophosphorane 2 (Scheme ) 12.…”