To produce a quinic acid derivative useful as a pharmaceutical intermediate effectively at a low cost by converting a quinic acid component of a crude quinic acid containing an inorganic salt in a large amount extracted from an extraction resource into a corresponding ester and acetalizing the obtained ester.
In a liquid of a raw material containing quinic acid, (A) the quinic acid is made to react with (B) an alcohol in the presence of an acid or base catalyst into a quinic acid ester, and subsequently the ester is made to react with (C) a ketone derivative or an aldehyde derivative in the presence of an acid catalyst to obtain an acetal of the quinic acid ester of formula I (R1 and R2 are each H, an alkyl, an aryl or the like; R3 is an alkyl, an alkenyl or the like). The component C is preferably a compound of formula II (R' and R" are each an alkyl, an alkenyl or the like). Further, a protecting group is introduced into an acetal of formula I in the presence of a base to convert into a quinic acid derivative of formula III (R4 is a protecting group of the hydroxy group), thereafter the product is made to react with a reagent having dehydrating activity, subsequently the protecting group is removed, and as the result, a precursor of shikimic acid can be obtained.
TSURU KAZUTAKA
SHIOYA MASAHIRO
