Stereoselective Synthesis of Fully Protected (S)-1,7-Dioxaspiro[5,5]undec-4-ene Derivatives of Sugars
作者:Romualdo Caputo、Umberto Ciriello、Pasquale Festa、Annalisa Guaragna、Giovanni Palumbo、Silvana Pedatella
DOI:10.1002/ejoc.200300025
日期:2003.7
Perbenzylated 1,7-dioxaspiro[5,5]undec-4-ene derivatives of sugars are obtained in three steps, starting from fully protected glycono-1,5-lactones. The procedure is based on the attack of a lithiated dithiinyl reagent (6) on the starting δ-glyconolactone. The C-glycosidation leads to the sole thermodynamically more stable α-hemiacetal derivative, the spirocyclization of which is then accomplished with
从完全保护的 glycono-1,5-内酯开始,分三步获得全苄化 1,7-二氧杂螺[5,5]十一碳烯衍生物。该程序基于锂化二噻吩基试剂 (6) 对起始 δ-乙醇酸内酯的攻击。C-糖苷化导致唯一的热力学更稳定的α-半缩醛衍生物,然后用BF3·Et2O 完成其螺环化。完全保护的不饱和螺缩醛可以顺利脱硫,以便进一步研究游离双键。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)