Methanesulfonic Acid → 1,1-Dimethylethyl (4R,6R)-6-(cyanomethyl)-2,2-dimethyl-1,3-dioxane-4-acetate

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Reaction Steps

Crude [R-(R*,R*)]-1,1-dimethylethyl 6-cyano-3,5-dihydroxyhexanoate (about 150 moles) from Step (2) is diluted with 100 kg of 2,2-dimethoxypropane and acidified with about 1 L of methanesulfonic acid. The reaction is quenched by the addition of aqueous sodium bicarbonate solution and concentrated by vacuum distillation. The residue is diluted with 150 L of hexane, and the layers separated. The organic layer is washed with aqueous sodium bicarbonate solution and cooled to 0° C.±10° C. to crystallize. The product is collected by filtration and washed with cooled hexane, then dried affording 28.5 kg of (4R cis) 1,1-dimethylethyl 6-cyanomethyl-2,2-dimethyl-1,3-dioxane-4-acetate.

Provenance & Evidence