The present invention is to provide a production technology by which an
optically active 2-[6-(
hydroxymethyl)-1,3-dioxan-4-yl]
acetic acid derivative, which are of value as pharmaceutical intermediates, can be produced from inexpensive and readily available starting materials without using any extraordinary equipment such as an ultra-low-temperature reactor. The present invention is a production process of an
optically active 2-[6-(
hydroxymethyl)-1,3-dioxan-4-yl]
acetic acid derivative which comprises reacting an enolate, prepared by permitting a base or a 0-valent
metal to act on an
acetic acid ester derivative with (S)-β-hydroxy-γ-butyrolactone at a temperature not lower than −30° C. to give a dihydroxyoxohexanoic
acid derivative, treating the same with an acylating agent in the presence of a base to produce a dihydroxyoxohexanoic acid monoacyl derivative, reducing this compound with a
microorganism to produce a trihydroxyhexanoic acid monoacyl derivative, treating this compound with an
acetal-forming
reagent in the presence of an acid catalyst to produce an acyloxymethyldioxanylacetic
acid derivative, and finally, subjecting this compound to
solvolysis in the presence of a base.