(9Z)- and (11Z)-8-Methylretinals for Artificial Visual Pigment Studies: Stereoselective Synthesis, Structure, and Binding Models
作者:Rosana Alvarez、Marta Domínguez、Yolanda Pazos、Fredy Sussman、Angel R. de Lera
DOI:10.1002/chem.200304847
日期:2003.12.5
Artificial visual pigment formation was studied by using 8-methyl-substituted retinals in an effort to understand the effect that alkyl substitution of the chromophore side chain has on the visual cycle. The stereoselective synthesis of the 9-cis and 11-cis isomers of 8-methylretinal, as well as the 5-demethylated analogues is also described. The key bond formations consist of a thallium-accelerated
为了理解发色团侧链的烷基取代对视觉循环的影响,通过使用8-甲基取代的视网膜研究了人工视觉色素的形成。还描述了8-甲基视网膜的9-顺式和11-顺式异构体的立体选择性合成,以及5-脱甲基化的类似物。关键键的形成包括环己烯基硼酸和二烯基碘化物(C6-C7)之间的a加速的Suzuki交叉偶联反应,以及高度立体控制的Horner-Wadsworth-Emmons或Wittig缩合(C11-C12)。通过用B(OiPr)(3)或B(OMe)(3)捕获前体环己烯基锂物质来制备环己烯基硼酸。环己烯基锂物种本身是通过nBuLi诱导的三糖基elimination的消除(Shapiro反应)获得的,或取决于环的空间位阻,通过碘-金属交换。在载脂蛋白视蛋白的结合实验中,只有9-顺5-去甲基8-甲基视网膜产生了人工色素。9-顺式-8-甲基视网膜仅提供残余结合,而没有发现11-顺式类似物形成人工色素的证据。基于分子力