Chemoenzymatic and yeast-catalysed synthesis of diastereomeric ethyl γ-phenyl and γ-(n-pyridyl)paraconates
作者:Cristina Forzato、Giada Furlan、Patrizia Nitti、Giuliana Pitacco、Ennio Valentin、Ennio Zangrando、Pietro Buzzini、Marta Goretti、Benedetta Turchetti
DOI:10.1016/j.tetasy.2008.08.011
日期:2008.9
The synthesis of γ-phenyl and γ-(n-pyridyl)paraconates was accomplished by chemical reduction of their respective ketodiester precursors followed by cyclisation of the resulting hydroxy diester intermediates. The cis- and trans-lactones thus obtained were separated and separately subjected to enzymatic hydrolysis with HLAP. The cis-lactonic esters had enantiomeric excesses ranging from 94% to 99%,
γ-苯基和γ-(n-吡啶基)对羟基甲酸酯的合成是通过化学还原它们各自的酮二酯前体,然后环化所得的羟基二酯中间体而完成的。分离由此获得的顺式和反式内酯,并分别用HLAP进行酶水解。所述CIS -lactonic酯具有对映体过量范围从94%至99%,而对于反式-异构体的ee值介于真实从80%至93%。将相同的酮二酸酯前体用一系列酵母进行还原。反式的绝对配置通过对其氢溴酸盐的X射线分析确定了-(-)-2-吡啶基对圆锥体酸,而其他内酯的绝对构型则通过分析其各自的CD曲线来确定。