The present invention relates to methods for the preparation of diastereomerically pure (3R,3aS,6aR) hexahydro-furo[2,3-b]furan-3-ol (6) as well as a novel intermediate, (3aR,4S,6aS) 4-methoxy-tetrahydro-furo[3,4-b]furan-2-one (4) for use in said methods. More in particular the invention relates to a stereoselective method for the preparation of diastereomerically pure (3R,3aS,6aR) hexahydro-furo[2,3-b]furan-3-ol, as well as methods for the crystallization of (3aR,4S,6aS) 4-methoxy-tetrahydro-furo[3,4-b]furan- 2-one and for the epimerization of (3aR,4R,6aS) 4-methoxy-tetrahydro-furo[3,4-b]-furan-2-one to (3aR,4S,6aS) 4-methoxy-tetrahydro-furo[3,4-b]furan-2-one.
本发明涉及制备对映异构体纯度高的(3R,3aS,6aR)六氢
呋喃[2,3-b]
呋喃-3-醇(6)的方法,以及用于该方法的新型中间体(3aR,4S,6aS) 4-甲氧基
四氢呋喃[3,4-b]
呋喃-2-酮(4)。更具体地说,本发明涉及一种立体选择性的制备对映异构体纯度高的(3R,3aS,6aR)六氢
呋喃[2,3-b]
呋喃-3-醇的方法,以及用于(3aR,4S,6aS) 4-甲氧基
四氢呋喃[3,4-b]
呋喃-2-酮的结晶方法和(3aR,4R,6aS) 4-甲氧基
四氢呋喃[3,4-b]-
呋喃-2-酮的外消旋化为(3aR,4S,6aS) 4-甲氧基
四氢呋喃[3,4-b]
呋喃-2-酮的方法。