Synthesis
Step G: 4-(4-methoxyphenyl)-4-oxobutanoic acid (40 g) was suspended in a solvent mixture of acetic acid (100 ml) and tetrahydrofuran (THF, 100 ml). To this suspension, 10% palladium-carbon catalyst (50% wet weight, 4 g) was added, followed by stirring the reaction mixture under hydrogen atmosphere (0.4 MPa) for 9 hours. Upon completion of the reaction, it was filtered through a diatomaceous earth pad to remove the catalyst. Toluene was added to the filtrate and the solvent was subsequently removed by distillation under reduced pressure to afford 4-(4-methoxyphenyl)butanoic acid in quantitative yield. The product was characterized by 1H-NMR (CDCl3): δ 1.89 (m, 2H), 2.32 (t, J=7.3 Hz, 2H), 2.58 (t, J=7.4 Hz, 2H), 3.73 (s, 3H), 6.78-6.82 (m, 2H), 7.03-7.08 (m, 2H), 10.96 (brs, 1H).
References
[1] Patent: EP1726587, 2006, A1. Location in patent: Page/Page column 33
[2] Chemistry of Natural Compounds, 2003, vol. 39, # 4, p. 404 - 406
[3] Indian Journal of Chemistry, Section B: Organic Chemistry Including Medicinal Chemistry, 1998, vol. 37, # 3, p. 281 - 284
[4] Research on Chemical Intermediates, 2017, vol. 43, # 10, p. 5933 - 5942
[5] Journal of Organic Chemistry, 1990, vol. 55, # 11, p. 3537 - 3543
