Synthetic studies on the avermectins: substituent effects on intramolecular Diels-Alder reactions of N-furfurylacrylamides and further reactions of the cycloadducts
作者:Michael E. Jung、Leslie J. Street
DOI:10.1021/ja00338a071
日期:1984.12
fifth C=C, neither of these structural elements are evidently essential for these functions of the pigment. A similar but more restrictive conclusion has been proposed for the 5,6-ethylene bond by our studies of the 5,6-dihydroretinal pigments.13 These results are consistent with isomerization and charge separation being thd primary event14 and indicate that the proton pumping and photocycling are dependent
80 K 处的样品。1558 cm-' 处的 CC 带代表最初的全反式颜料,而 1575 cm-* 处的 CC 带几乎肯定是由在约 10 处吸收的短波长 M 型中间体产生的。380 纳米。结果与先前确定的 A 和 C=C 拉伸频率之间的相关性与 M 形成的预期温度依赖性一致。 12 将 2-4 的 6-cis 和 2,6-dicis 异构体与细菌素结合,广泛的吸收是标有 450-460 nm 的 A, ,肩峰位于 510 nm。用二氯甲烷萃取颜料产生各自的6-顺式或2,6-二顺式异构体。这些色素会被羟胺或全反式视黄醛迅速(5 分钟)破坏。在辐照时,吸收移至 487 nm,强度增加,与全反式颜料的吸收相同。当这些经辐照的颜料用二氯甲烷萃取时,仅获得相应的全反式异构体。这些结果表明,形成了 6-顺和 2,6-dicis-2-4 视黄醛和细菌视蛋白的不稳定缔合体,这可能是由于缺少环己基环而导致的