Tandem Pummerer/Mannich Cyclization Cascade of α-Sulfinylamides as a Method To Prepare Aza-Heterocycles
作者:Albert Padwa、Todd M. Heidelbaugh、Jeffrey T. Kuethe、Michael S. McClure、Qiu Wang
DOI:10.1021/jo020083x
日期:2002.8.1
particularly suited for the assembly of natural product scaffolds. Some preliminary studies were directed toward both mesembrine and deethylibophyllidine. When the model Z-enamido sulfoxide 33 was heated with p-TsOH, a 80% yield of tosylate 34 was obtained as a single diastereomer. In this case, the carbocation intermediate derived from cyclization onto the terminal pi-bond was trapped with p-TsOH from the least
通过伯胺与酮的缩合,然后使所得的亚胺与乙基亚磺酰基乙酰氯反应,然后用高碘酸钠氧化,可以方便地制备一系列α-亚磺酰胺基。当用p-TsOH处理时,通过涉及初始Pummerer反应,随后将所得N-酰基亚胺离子随后环化到束缚的芳族环上的机理发生环化以产生稠合的异喹啉内酰胺。根据Nazarov型4pi-电环反应,然后将pi环化到N-酰基亚胺离子受阻最小的一侧,合理化了单个非对映异构体的分离。用于产生α-酰基硫鎓离子中间体的另一种方法涉及双(乙基亚硫酰基乙酰基)乙酰胺与四氟硼酸二甲基(甲基)硫代on(DMTSF)的反应。用DMTSF处理数种双-乙基亚磺酰胺通过相关方法以高收率递送了新颖的螺-杂环作为单一非对映异构体。与该级联序列相关的收敛性和立体化学控制使其特别适合于天然产物支架的组装。一些初步的研究针对了甲基安息香和去甲异叶核苷。当将模型Z-en氨基亚砜33与对-TsOH一起加热时,作为单一非对映异