difluorotrimethylsilicate (TAS-TMSF2) mediated reaction of dialkyl substituted trimethylsilyl ketene acetals 4 or 6 with aldonolactones 1, 9 or 11 affords dimers 8, 10 and 12 in an unprecedented but diastereoselective manner. In addition, under the same conditions the reaction of a suitable protected aldonolactone with a cyclic trimethylsilyl ketene acetal 14 results in a diastereoselective chain elongation thus creating
三(二甲基
氨基)锍difluorotrimethylsilicate(TAS-TMSF 2)的二烷基取代的三甲基
硅烷基
乙烯酮缩醛介导的反应4或6具有aldonolactones 1,9或11点得到的二聚体8,10和12以一种前所未有的非对映选择性,但方式。另外,在相同条件下,合适的受保护的醛糖内酯与环状三甲基甲
硅烷基烯酮
缩醛14的反应导致非对映选择性的链延长,因此非对映地产生两个新的立体异构中心。