O-Benzyl protected pyranoid ene lactones (5,6-dihydro-2H/-pyran-2-ones) 4a-c, 8 were obtained in high yield in a two-step procedure. Treatment of the phenyl glycosyl sulfones 2a-d, 6, which were readily prepared from their corresponding sulfides, with lithium diisopropylamide (LDA) at -90°C afforded the elimination products 3a-c, 7. These intermediates were then treated with sodium methoxide in the presence of dicyclohexano-18-crown-6 to give the compounds 4a-c, 8.
通过两步法,高产率地获得了 O-苄基保护的
吡喃烯内酯(5,6-二氢-2H/-
吡喃-2-酮)4a-c、8。 苯基糖基砜 2a-d, 6 很容易从其相应的
硫化物中制备出来,在 -90°C 下用
二异丙基酰胺
锂 (
LDA) 处理这些中间产物,可得到消除产物 3a-c, 7。