Dipartimento di Chimica, Università di Torino , via P. Giuria 7, 10125 Torino, Italy.
J Org Chem. 2013 Nov 1;78(21):11007-16. doi: 10.1021/jo4019914. Epub 2013 Oct 14.
The gold(I)-catalyzed cyclization of N-Boc-protected 6-alkynyl-3,4-dihydro-2H-pyridines, prepared by the Sonogashira coupling of lactam-derived enol triflates or phosphates, provides vinylogous amides, which are useful intermediates in the synthesis of natural compounds. The Au(I)-catalyzed reaction is carried out with Ph3PAuOTf as a catalyst and proceeds via a 6-endo-dig cyclization to form a vinylgold species that after protodeauration generates a cyclic carbamate intermediate. This intermediate is in most cases not isolated, but the addition of a base to the reaction mixture rapidly and quantitatively delivers the target vinylogous amide. The first synthesis of a natural compound from Sonneratia hainanensis has been accomplished by this approach.
金（I）催化的 N-Boc 保护的 6-炔基-3,4-二氢-2H-吡啶的环化反应，通过酰胺衍生的烯醇三氟甲磺酸酯或膦酸盐的 Sonogashira 偶联制备，提供了 vinylogous amides，这是天然化合物合成中的有用中间体。Au（I）催化反应使用 Ph3PAuOTf 作为催化剂进行，通过 6-endo-dig 环化反应形成 vinylgold 物种，该物种在质子化去金后生成环状氨基甲酸酯中间体。该中间体在大多数情况下未被分离，但向反应混合物中加入碱可迅速定量地得到目标 vinylogous amide。通过这种方法，首次完成了来自海南海桑的天然化合物的合成。
