DL-2-Phenoxypropionic acid → 3-(4-Benzyloxy-3-methoxyphenyl)-3-hydroxy-2-methyl-2-phenoxypropionic Acid

Beteiligte Stoffe

Reaktionsschritte

A stirred solution of LDA in cyclohexane (1.5 M) was cooled to −20° C., to which a solution of 2-phenoxypropionic acid (10 g, 60.2 mmol) in THF (80.3 mL) was slowly added, keeping the temperature below −10° C. The resulting dianion solution was stirred for 15 min, then a solution of 4-benzyloxy-3-methoxybenzaldehyde (14.58 g, 60.2 mmol) in THF (80.3 mL) was added over 1 h, maintaining temperature below −10° C. Fifteen minutes after completion of aldehyde addition, the reaction mixture was poured onto ice water (200 mL), and extracted using 1:2 Et2O:hexane (500 mL). The aqueous layer was isolated, extracted again with 1:2 Et2O:hexane (240 mL), then acidified with concentrated HCl until pH=3. The product acid was extracted into ethyl acetate (2×165 mL), which was dried over Na2SO4 and concentrated to an orange paste (16.5 g crude, 67%): MS (EI) 426.2 (M+NH4)+, 407.2 (M−H)−.

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