A palladium-catalyzed domino process for the quick assembly of tricyclic-fused heterocycles starting from aryl iodides and functionalized isocyanides containing a disubstituted terminal alkene has been developed. The process is triggered by intermolecular isocyanide insertion, followed by Heck-type carbopalladation of the intramolecular alkene moiety and subsequent C(sp2)–H activation. Moreover, an
The Synthetic Intermediate of Pyridoxine. II. The Thermal Cyclization of Ethyl α-Isocyanopropionate to 5-Ethoxy-4-methyloxazole
作者:Itsutoshi Maeda、Kazushi Togo、Ryonosuke Yoshida
DOI:10.1246/bcsj.44.1407
日期:1971.5
product, II, was 20%; unreacted I (30%), ethyl α-cyanopropionate(20%), and dimer of I (5%) were also obtained. The α-hydrogen of ethyl α-isocyanosuccinate (X) can be more easily removed than that of I, so X may be expected to be more readily converted to 5-ethoxy-4-ethoxycarbonylmethyloxazole (XI), which is also an intermediate of pyridoxine. The yield of XI from X did not exceed 30% because of the
α-异氰基丙酸乙酯 (I) 热环化生成 5-乙氧基-4-甲基恶唑 (II) 作为合成吡哆醇的中间体。也进行了几种新的α-异氰基羧酸烷基酯与相应的5-烷氧基-4-取代的恶唑的类似反应。研究了I的热环化反应产物。180℃环化5小时,主产物II的最大收率为20%;还得到了未反应的 I (30%)、α-氰基丙酸乙酯 (20%) 和 I 的二聚体 (5%)。α-异氰基琥珀酸乙酯 (X) 的 α-氢比 I 更容易去除,因此可以预期 X 更容易转化为 5-乙氧基-4-乙氧基羰基甲基恶唑 (XI),它也是吡哆醇。
The Synthetic Intermediate of Pyridoxine. III. The Simple Synthesis of Ethyl<i>N</i>-Ethoxalylalaninate and Ethyl<i>N</i>-Formylalaninate
作者:Itsutoshi Maeda、Soichiro Asai、Hideshi Miyayashiki、Ryonosuke Yoshida