Optical resolution and absolute stereochemistry of trans-2,5-dimethyl-1-phenyl-1-silacyclopentane
作者:Hai-Shan Dang、Brian P. Roberts、Derek A. Tocher
DOI:10.1039/p19950000117
日期:——
chromatography and the molecular structure of the (2S,5S)-silyl ether was determined by single-crystal X-ray diffraction. Reduction of this diastereoisomer with LiAlH4 afforded (2S,5S)-(+)-DMPSC, [α]D22+27.8 (c 2.16, cyclohexane), with an estimated enantiomeric excess of >98%. The (2R,5R)-(–)-enantiomer was prepared in a similar manner using (R)-TPED as the resolving agent, which was readily recovered in
通过使2,5-二溴己烷和二氯苯基硅烷与镁在四氢呋喃中反应,以立体异构体的混合物的高产率制备了2,5-二甲基-1-苯基-1-硅杂环戊烷(DMPSC)。如此制得的硅烷由约1。1:1:3的混合物的顺式-异构体2,3和外消旋的反式-异构体4 + 5分别。用铜该产品的处理(II)在乙腈氯化给出1-氯DMPSC作为混合物的顺式-异构体6,7和外消旋的反式-异构体8 + 9以大约1:6:12的比例。单ø二甲酯-silylation大号用氯硅烷的混合物-酒石酸盐,得到甲硅烷基醚11和非对映异构对反式-化合物12和13为结晶固体。顺式-甲硅烷基醚11的分子结构已经通过X射线衍射确定。(2 S)-1,1,2,三苯乙烷-1,2-二醇[(S)-TPED]选择性地出现在受阻较少的仲OH基团上; 通过重结晶和柱色谱法分离立体异构产物,并通过单晶X射线衍射确定(2 S,5 S)-甲硅烷基醚的分子结构。用LiAlH 4还原该非对映异构体得到(2