反应详情

To a stirred -50° C. solution of tertiary-butyl acetate (60 mL, 0.44 mol), (R)-4-cyano-3-hydroxybutyric acid, n-butyl ester (20 g, 0.11 mol) and 150 mL tetrahydrofuran is added lithium diisopropylamide (300 mL of 1.5 M) in tetrahydrofuran over 15 minutes and the mixture is stirred at -45° C. to -50° C. for 90 minutes. To this solution is added 700 mL of 5% aqueous hydrochloric acid solution along with 300 mL of ethyl acetate. The aqueous layer is separated and the remaining top layer washed with aqueous sodium chloride solution. The organic layer is then concentrated in vacuo to afford crude (5R)-1,1-dimethylethyl 6-cyano-5-hydroxy-3-oxo-hexanoate which is not isolated, and is carried on to (4R-cis)-1,1-dimethylethyl 6-cyanomethyl-2,2-dimethyl -1,3-dioxane-4-acetate as described in Example 2. TLC: Rf =0.15 (1:1 ethyl acetate: hexanes) on a Kieselgel 60 F254 0.254 mm silica thin layer plate.

1. customThe aqueous layer is separated
2. washthe remaining top layer washed with aqueous sodium chloride solution
3. concentrationThe organic layer is then concentrated in vacuo