Method for preparing 1,6:2,3-dianhydro-β-D-mannopyranose
View Patent ↗The invention relates to a method for preparing 1,6:2,3-dianhydro-â-D-mannopyranose and is characterized in that it includes a step of cyclizing the compound C, where R is an alykyl group and R′ is an activating agent, in an alcohol/alcoholate mixture under anhydrous conditions.
1. A process for the preparation of compound (I):
comprising a stage of cyclisation of compound C:
in which R represents an alkyl group comprising from 1 to 4 carbon atoms and R′ represents an activating agent, in an alcohol/alkoxide mixture under anhydrous conditions.
2. The process according to claim 1 , wherein in the compound C, R represents a methyl group.
3. The process according to claim 1 or claim 2 , wherein in the compound C, R′ represents a tosyl, mesyl or benzenesulphonyl group.
4. The process according to any one of claim 1 or 2 wherein the compound C corresponds to the formula C′:
in which Ac represents an acetyl group and Ts represents a tosyl group.
5. The process according to any one of claim 1 or 2 wherein the cyclisation stage is carried out in a methanol/sodium methoxide mixture.
6. The process according to any one of claim 1 or 2 wherein the cyclisation stage is carried out using from two to three equivalents of alkoxide.
7. The process according to claim 1 further comprising:
a stage of acylation of compound B:
in which R′ is as defined in claim 1 , making it possible to obtain the compound C as defined in claim 1 ,
followed by the stage of cyclisation, as defined in claim 1 , of compound C.
8. The process according to claim 7 , wherein the compound B is such that R′ represents a tosyl group and corresponds to the formula B′:
9. The process according to claim 7 or claim 8 , characterized in that the acylation stage is an acetylation reaction.
10. The process according to claim 9 , characterized in that the acetylation reaction is carried out using acetic anhydride.
11. The process according to claim 1 further comprising:
a stage of activation of compound A:
to obtain compound B:
In which R′ is as defined in claim 1
followed by a stage of acylation, of compound B, to obtain compound C as defined in claim 1 ,
followed by a stage of cyclisation, as defined in claim 1 , of compound C.
12. The process according to claim 11 , characterized in that the stage of activation of compound A is carried out using a tosyl, mesyl or benzenesulphonyl halide.
13. The process according to claim 7 further comprising:
a stage of activation of compound A:
to obtain compound B as defined in claim 7 ,
followed by a stage of acylation, as defined in claim 7 , of compound B, to obtain compound C:
followed by a stage of cyclisation of compound C to obtain compound (I):