2-(3,4-Dichloro-phenylamino)-propionic Acid → 2-(3,4-Dichloro-phenylamino)-propan-1-ol

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Reaction Steps

33.11 ml (33.11 mmol, 1 M in THF) of a borane-tetrahydrofuran complex solution was added dropwise at 0° C. to a solution of 3.10 g (13.24 mmol) 2-(3,4-dichloro-phenylamino)-propionic acid (synthesized in analogy to intermediate 11, with 3,4-dichloroiodobenzene, D-alanine and copper(I) iodide, 2-hydroxybenzaldehyde phenylhydrazone and tri-potassium phosphate in N,N-dimethylformamide; enantiomeric ratio 71:29) in 50 ml THF, then after 10 min the ice bath was removed and the solution stirred for 2 h at RT. After cooling, 22 ml of MeOH and 1.1 ml of H2SO4 were added, and after 30 min at RT and 1 h at reflux the reaction mixture was concentrated in vacuo. The residue was partitioned between NaCl sat. 1 M aq. sodium hydroxide solution and EtOAc (3×). The organic layer was washed with brine, dried (Na2SO4), filtered, and evaporated. Flash silica gel column (CH2Cl2/MeOH 99:1→98:2) afforded 2.90 g (99%) of the title compound as a 71:29 mixture of the (R) and (S) stereoisomers. Yellow oil, MS: 220.0 (MH+, 2Cl)

Provenance & Evidence