The general procedure for the synthesis of (3S,3aR,6R,6aR)-6-methoxyhexahydrofuro[3,2-b]furan-3-ol, (3R,3aR,6S,6aR)-6-methoxyhexahydrofuro[3,2-b]furan-3-ol, and isosorbide dimethylether using ethylene glycol dimethyl ether and isosorbide as raw materials is as follows: isosorbide, 1,2-dimethoxyethane ( ethylene glycol dimethyl ether) and heteropolyacid were sequentially added into a stainless steel high-pressure reactor and the reactor was sealed. The reaction mixture was magnetically stirred at 150°C for 5 hours. The molar ratio of 1,2-dimethoxyethane to isosorbide was 20:1, and the mass ratio of heteropolyacid to isosorbide was 0.2:1. After the reaction was completed, the reactor was cooled to room temperature. The reaction mixture was analyzed using gas chromatography, and the conversion and yield of the methylated product of isosorbide was calculated as molar percentage (mol%) by internal standard method.
