(4R-cis)-6-Hydroxymethyl-2,2-dimethyl-1,3-dioxane-4-aceticacid, 1,1-dimethylethyl ester CAS:124665-09-0 (4R-cis)-6-羥甲基-2,2二甲基-1,3-二氧六環(huán)-4-乙酸叔丁酯