Benzenesulfonic acid, 4-methyl-, compd. with pyridine (1:1) → HCID 57633597, compound

Participants

Reaction Steps

To a solution of 4-benzyloxy-6-hydroxymethyl-2,3-dimethyl-phenol (52 mg, 0.20 mmol), prepared as in Example 29, in 0.5 mL of dry DMF was added the above dimethyl ketal, 4,4-dimethoxy-pentanoic acid ethyl ester (420 mg, 2.2 mmol) and 5 mg of pyridinium p-toluene sulfonate (PPTS). The mixture was stirred for 48 h and concentrated. The crude product was purified on silica gel column chromatography (8:1 hexane/EtOAc) to afford a clear oil containing the desired product and starting ketal material. This mixture was then dissolved in EtOH (5 mL) and hydrogenated in the presence of 10 mg of Pd/C for 1.5 h at atmosphere pressure. After filtration the solution was concentrated and purified by chromatography (5:1 hexane/EtOAc) to afford 3-(6-hydroxy-2,7,8-trimethyl-4H-benzo[1,3]dioxin-2-yl)-propionic acid ethyl ester as a light brown sticky oil (38 mg). 1H-NMR (300 MHz, CDCl3) δ (ppm): 6.29 (s, 1H), 4.77 (s, 1H), 4.72 (q, J=14.9, 2H), 4.13 (q, J=7.2, 2H), 2.57-2.52 (m, 2H), 2.22-2.16 (m, 2H), 2.16 (s, 3H), 2.10 (s, 3H), 1.47 (s, 3H), 1.27 (t, J=7.2, 3H); 13C-NMR δ (ppm): 173.8, 147.2, 142.5, 126.0, 122.8, 116.5, 107.5, 99.5, 60.5, 33.9, 28.6, 21.8, 14.2, 11.9, 11.5.

Provenance & Evidence