Easy and General Method for the Preparation of m‐ and p‐Acylbenzoic Acids: A New Synthesis of rac‐Suprofen

Abstract

A method for the preparation of m‐ and p‐acylbenzoic acids 3 based on the Claisen condensation of isophthalic or terephthalic diesters 1 with α‐methylenecarboxylic esters 2 is described. p‐Propionylbenzoic acid p‐4 (R = Me) is used in a new synthesis of rac‐suprofen (11).

Selective Oxidation of Acetophenones Bearing Various Functional Groups to Benzoic Acid Derivatives with Molecular Oxygen

“…Previously, we showed that THICA possesses a higher oxidizing ability than NHPI for the aerobic oxidation of polyA C H T U N G T R E N N U N G methylbenzenes. [10] Therefore, THICA was used in place of NHPI (entries [11][12][13][14][15]. As expected, the oxidation of 1a by THICA/CoA C H T U N G T R E N N U N G (OAc) 2 afforded selectively 2a in good yield (85%) (entry 11).…”

“…[9] In addition, Camps reported a method for 2b based on the Claisen condensation of isophthalic acid with methylene carboxylic esters. [13] The oxidation of 4-ethylacetophenone (1e) and 4-isopropylacetophenone (1f) gave rise to 1,4-diacetylbenzene (5) in 87% and 45% yields, respectively, under optimized reaction conditions (entries 5 and 6). We next tried the oxidation of various acetophenones with O 2 (1 atm) by MnA C H T U N G T R E N N U N G (OAc) 2 in acetic acid at 100 8C for 15 h (Table 3).…”

“…Infrared (IR) spectra were measured as thin films on NaCl plate or KBr press disk. 1 H and 13 C NMR spectra were measured at 270 and 67.5 MHz, respectively, in DMSO-d 6 or CDCl 3 with Me 4 Si as the internal standard. The products were characterized by 1 H NMR, 13 C NMR, and GC-MS.…”

“…1 H and 13 C NMR spectra were measured at 270 and 67.5 MHz, respectively, in DMSO-d 6 or CDCl 3 with Me 4 Si as the internal standard. The products were characterized by 1 H NMR, 13 C NMR, and GC-MS. The yields of products were estimated from the peak areas based on the internal standard technique using GLC after the esterification with MeOH (20 mL) and H 2 SO 4 (50 mg) at 100 8C for 24 h.…”

Thallium(III) in Organic Synthesis

“…In recent years, several papers dealing with the conversion of alkyl aryl ketones into the corresponding carboxylic acids or esters have been published. [27][28][29][30][31][32][33] Illustrative examples are given in Scheme 6. The most common conditions involve the use of TTN in MeOH/TMOF (trimethylorthoformate) or in MeOH/HClO 4 .…”