Uses
7-Fluoro-1-tetralone was prepared from 3-(4-fluorobenzoyl)-propionic acid by Wolff-Kishner reduction followed by ring closure with polyphosphoric acid and other substituted 1-tetralones where commercially available. Reduction of 3-(4-fluorobenzoyl)propionic acid with an excess of tert-butylamine borane (TBAB) in the presence of AlCl3 provided 4-(4-fluorophenyl)-1-butanol (87) in 63% yield for the synthesis of LM-1507 sodium salt. Penfluridol 1-[4,4-bis(4-fluorophenyl)butyl]-4-(4-chloro-3-trifluoromethylphenyl)- 4-hydroxypiperidine, C 28 H 27 ClF 5 NO, M r 523.99, mp 105 - 107°C, is obtained by reducing the ketone of 3-(4-fluorobenzoyl)propionic acid into a lactone.
Synthesis
1. aluminum chloride (2.66 g, 20 mmol) was slowly added to a stirred mixture of succinic anhydride (1.00 g, 10 mmol) and fluorobenzene (5.6 mL, 60 mmol) at -5 °C.
2. the reaction temperature was maintained at -5 °C for 1 hour, followed by a slow warming to room temperature, and the reaction continued for 17 hours.
3. the reaction mixture was slowly poured into a stirred 18% HCl aqueous solution (30 mL) at 0 °C and stirring was continued for 30 min while the mixture was allowed to gradually warm up to room temperature.
4. The resulting white powder was collected by filtration and washed with deionized water. 5. The product was 4-(4-(4-hydroxyphenyl)ethyl)ethyl).
5. The product was 4-(4-fluorophenyl)-4-oxobutyric acid in 1.67 g, 85% yield. 6.
; HPLC tR = 1.53 min (>99% purity, mobile phase is an aqueous solution of 80% MeCN).
References
[1] Helvetica Chimica Acta, 1995, vol. 78, # 3, p. 647 - 662
[2] Patent: WO2007/96647, 2007, A2. Location in patent: Page/Page column 148-149
[3] Patent: CN107556287, 2018, A. Location in patent: Paragraph 0036; 0037; 0038; 0039; 0040; 0052; 0053
[4] Patent: CN106187863, 2016, A. Location in patent: Paragraph 0153; 0154; 0155; 0156; 0157; 0104-0108
[5] Tetrahedron Letters, 2016, vol. 57, # 24, p. 2583 - 2586
