反应详情

Crude 5R 1,1-dimethylethyl 6-cyano-5-hydroxy-3-oxohexanoate (about 150 moles) from Step (1) is dissolved in 325 L of tetrahydrofuran containing about 20 kg of triethylborane, stirred for about 2 hours at room temperature, cooled to ±75° C.±20° C. and diluted with 25 L of methanol and 8 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 optionally quenched by the addition of 3 kcg of acetic acid and 10 L of methanol and concentrated by vacuum distillation, saving the distillate. The residue is dissolved in methanol and acetic acid, optionally diluted with water, and concentrated by vacuum distillation, keeping this distillate separate from the first one. 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.

1. temperaturecooled to ±75° C.±20° C.
2. additionAfter the addition
3. temperaturethe reaction mixture is warmed to 0° C.±25° C
4. customThe reaction mixture is optionally quenched by the addition of 3 kcg of acetic acid and 10 L of methanol
5. concentrationconcentrated by vacuum distillation
6. dissolutionThe residue is dissolved in methanol
7. additionacetic acid, optionally diluted with water
8. concentrationconcentrated by vacuum distillation
9. customthis distillate separate from the first one
10. dissolutionThe residue is dissolved in methanol
11. concentrationconcentrated by vacuum distillation
12. dissolutionThe residue is dissolved in a mixture of water and ethyl acetate
13. customthe aqueous layer separated
14. concentrationThe organic layer is concentrated by vacuum distillation
15. dissolutionThe residue is dissolved in methanol
16. concentrationacetic acid and concentrated by vacuum distillation
17. dissolutionThe residue is dissolved in ethyl acetate
18. concentrationconcentrated by vacuum distillation