Acetic Acid → 1,1-Dimethylethyl 6-cyano-3,5-dihydroxyhexanoate

Participants

Reaction Steps

Crude 5R 1,1-dimethylethyl 6-cyano-5-hydroxy-3-oxohexanoate (about 150 moles) from Step (1) is dissolved in the first distillate from Step (a) along with 50 L of tetrahydrofuran, cooled to −75° C.±20° C., and optionally diluted with 25 L of methanol, and 10 kg of acetic acid. Sodium borohydride (8 kg) as a solution in methanol and aqueous sodium hydroxide is added slowly. After the addition, the reaction mixture is warmed to 0° C.±25° C. The reaction mixture is quenched by the addition of 10 kg of acetic acid and 20 L of methanol and concentrated by vacuum distillation. The residue is dissolved in methanol and acetic acid, optionally diluted with water, and concentrated by vacuum distillation. The residue is dissolved in methanol and concentrated by vacuum distillation. The residue is dissolved in a mixture of water and ethyl acetate, and the aqueous layer separated. The organic layer is concentrated by vacuum distillation. The residue is dissolved in methanol and acetic acid and concentrated by vacuum distillation. The residue is dissolved in ethyl acetate and concentrated by vacuum distillation affording crude [R—(R*,R*)]-1,1-dimethylethyl 6-cyano-3,5-dihydroxyhexanoate.

Provenance & Evidence