Syntheses of Bile Pigments. Part 17. Synthesis of a non-racemizable urobilin derivative
作者:Lubomir Floch、Fredy Nydegger、Albert Gossauer、Christoph Kratky
DOI:10.1002/hlca.19940770205
日期:1994.3.23
the eleven-step synthesis of 7 is the 1,4,5,10-tetrahydro-10-hydroxy-1-oxo-11H-dipyrrin-9-carboxylate rac-2, which could be resolved into enantiomers by fractional crystallization of the corresponding methyl N-[1-(naphth-1-yl)ethyl]carbamates 3 and 4. The absolute configuration of enantiomerically pure (−)-2 was determined by X-ray diffraction analysis of its camphor-10-sulfonate 5. As the CD spectrum
合成了具有光学活性的尿嘧啶模型化合物7,其中Me基团代替H原子与不对称中心键合,从而防止了互变异构引起的手性损失。7的11步合成的关键中间体是1,4,5,10-四氢-10-羟基-1-氧代-11 H-二吡喃-9-羧酸盐rac - 2,可通过拆分为对映体N- [1-(萘-1-基)乙基]氨基甲酸甲酯3和4的分步结晶。对映体纯的(-)- 2的绝对构型是通过对其樟脑10磺酸盐的X射线衍射分析确定的5。由于从(-)-(R)-2获得的尿嘧啶类似物7的CD光谱显示出正的Cotton效应,因此,与先前的工作相关,本结果证明,用Me基团取代了与H原子键合的H原子。手性尿嘧啶发色团的不对称中心不影响后者的绝对构型与其螺旋度之间的关系。