| 摘要 |
A method for the preparation of (S)-alcohol oxazolidides of general formula II, in which PG represents hydrogen or a hydroxyl protecting group, such as trimethylsilyl, tert-butyldimefhylsilyl, benzyloxycarbonyl, tert-butoxycarbonyl, benzyl, benzhydryl or trityl, in which a ketal oxazolidide of general formula III, where PG has the same meaning as above and R means an alkyl with 1-4 carbon atoms, linear or branched, such as methyl, ethyl, isopropyl or butyl, or R+R together represents a divalent alkyl, or substituted with 1 or 2 alkyl groups, e.g. 1,2-ethylene, 1,2-propylene, 1,2-butylene, 1,3-propylene or 2,2-dimethyl-1,3-propylene, is deprotected by the action of acidic reagents in a mixture of water and a water-miscible solvent in the temperature range of 0 to (stage A), and the obtained ketone oxazolidide of general IV, in which PG has the same meaning as above, is reduced with asymmetrical reagents in an inert organic solvent in the temperature range of -30 to + (stage B). |
