The known aldehyde methyl
2,3,4-tri-O-methyl-α-D-gluco-hexodialdo-1,5-pyranoside
(9) was converted in eight steps into the 6-phenyl glucose-derived enolic
ortho ester (Z)-1,6-dideoxy-1,1-ethylenedioxy-
2,3,4-tri-O-methyl-6-phenyl-D-xylo-hex-5-enopyranose
(22), the geometry of which was established by a single-crystal X-ray study.
Treatment of the 6-phenyl enolic ortho ester (22) with titanium tetrachloride
at –78° effected clean rearrangement into
(2R/S,4R,5R,6S)-3,3-ethylenedioxy-4,5,6-trimethoxy-2-phenylcyclohexanone
(26). Reaction of (22) with methylmagnesium iodide gave
(1R,2S,4R,5S,6S)-3,3-ethylenedioxy-4,5,6-trimethoxy-1-methyl-2-phenylcyclohexanol
(24), the structure and stereochemistry of which were established by an X-ray
study. Reaction of (22) with phenylmagnesium bromide gave (25), the 1-phenyl
analogue of (24). The firmly established structure of (24) led to proof both
chemically and by X-ray means that the product from reaction of
1,6-dideoxy-1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-xylo-hex-5-enopyranose
(5) with methylmagnesium iodide has the hydroxy acetal structure (7) rather
than the originally assigned hemiacetal structure (3).
已知的醛甲基
2,3,4-三-O-甲基-α-D-葡萄糖-1,5-吡喃二糖苷
(9) 经过八个步骤转化为 6-苯基葡萄糖衍生的烯醇
正酯(Z)-1,6-二脱氧-1,1-亚乙二氧基-1,5-吡喃糖苷(9)。
2,3,4-tri-O-methyl-6-phenyl-D-xylo-hex-5-enopyranose
(22),其几何形状是通过单晶 X 射线研究确定的。
用四氯化钛在 -78° 下处理 6-苯基烯醇原酯 (22)
在 -78° 温度下进行处理,可将 6-苯基烯醇原酯 (22) 干净地重排为
(2R/S,4R,5R,6S)-3,3-亚乙二氧基-4,5,6-三甲氧基-2-苯基环己酮 (26)。
(26).将(22)与甲基碘化镁反应,得到
(1R,2S,4R,5S,6S)-3,3-亚乙二氧基-4,5,6-三甲氧基-1-甲基-2-苯基环己醇(24)。
(24),其结构和立体化学特征已通过 X 射线研究确定。
研究。将(22)与苯基溴化镁反应,得到了(25),即(24)的 1-苯基类似物。
类似物。(24)的结构已牢固确立,这就从化学和 X 射线两方面证明了
的反应产物。
1,6-二脱氧-1,1-亚乙二氧基-2,3,4-三-O-甲基-D-氧代-己-5-烯吡喃糖(5)与甲基镁的反应产物
(5) 与甲基碘化镁反应生成的产物具有羟基缩醛结构 (7),而不是最初指定的半缩醛结构
而不是最初指定的半缩醛结构 (3)。