作者:Angeles Martín、José A. Salazar、Ernesto Suárez
DOI:10.1021/jo960060g
日期:1996.1.1
Chiral spiroacetals of the 1,7-dioxaspiro[5.5]undecane, 1,6-dioxaspiro[4.5]decane, and 1,6-dioxaspiro[4.4]nonane types have been prepared from carbohydrates in pyranose or furanose forms. The spirocyclization reaction has been accomplished from a conveniently homologated carbohydrate by an intramolecular hydrogen abstraction reaction promoted by alkoxy radicals. Thus, 2,3,4,6-tetra-O-benzyl-1-deox
由吡喃糖或呋喃糖形式的碳水化合物制备了1,7-二氧杂螺[5.5]十一烷,1,6-二氧杂螺[4.5]癸烷和1,6-二氧杂螺[4.4]壬烷类型的手性螺缩醛。螺环化反应已经通过由烷氧基自由基促进的分子内氢提取反应,从便利地同源的碳水化合物完成。因此,在(二乙酰氧基碘)苯存在下,用可见光光解2,3,4,6-四-O-苄基-1-脱氧-1-(3'-羟丙基)-α-D-吡喃葡萄糖(2)。和碘制得(1R)-(3)和(1S)-2,3,4,6-四-O-苄基-1-脱氧-D-吡喃葡萄糖-1-螺-2'-四氢呋喃的混合物( 4)。甲基6-脱氧-6-(2'-羟乙基)-2,3,4-三-O-甲基-α-D-吡喃葡萄糖苷(8)的光解得到异构的螺缩醛甲基(5S)-(9)和(5R)-6-脱氧-5,2'-环氧-6-乙基-2,3,4-螺-O-甲基-α-D-吡喃葡萄糖苷(10)的螺中心现在位于C-5。[5.5]十一烷系列的螺缩醛:甲基(5R)-(19)和(5S)-6-脱氧-5