黑色的3,3'-二乙酰基-5,5'-双乙氧基羰基葡糖酮(二乙基月桂酸烯醇)的单晶X射线研究证实了烯醇结构(1)。异常短的分子间接触表明共轭分子将通过分子平面上方和下方的自电荷转移相互作用而连接,从而通过晶体形成线性但呈“ Z字形”排列。绿屈菜酮的1 H Nmr数据取决于溶剂,如果存在水分,干燥CDCl 3中桥质子的AMX系统(和其他信号)容易进入缓慢交换区域:添加碱会产生对称阴离子(AMA'桥质子) )并在[ 2 H 6] DMSO。3'-乙酰基-3,5,5'-三甲氧基羰基葡糖酮显示相关的1 H nmr行为,但3,3',5,5'-四基甲氧基羰基葡糖酮在CDCl 3中以7'-H形式(7)且对称存在以[ 2 H 6 ] DMSO的形式存在。各种溶剂中的电子光谱表明,青草酮在极性溶剂(蓝色)中被高度电离,在非极性溶剂(红色)中被离子化,在某些溶剂系统中会发生级联。青桂酮和黄嘌呤酮的13 C Nmr分配基于吡喃酮模型。
Polyketoenols and chelates. Glaucyrones and their reactions with magnesium methoxide
作者:S. Richard Baker、Leslie Crombie
DOI:10.1039/p19810000178
日期:——
complete ester exchange in the reaction of 3,3′-diacetyl-5,5′-bisethoxycarbonylglaucyrone (1) with excess of magnesiummethoxide, in accord with the mechanism proposed. On reaction with the latter reagent, the two new glaucyrones give aromatic penta-esters (11) and (14), and their mechanisms of formation are discussed. Heating these penta-esters effects cyclisation to xanthyrones having aromatic side-chain