Lewis-acid-induced reactions of α-methoxyglycinamide derivatives with silyl enol ethers. Formation of 3-amino-2-pyrrolidinones and 3-amino-2-pyrrolinones
作者:Eric C. Roos、Henk Hiemstra、W. Nico Speckamp、Bernard Kaptein、Johan Kamphuis、Hans E. Schoemaker
DOI:10.1002/recl.19921110705
日期:——
-methoxyacetamides were subjected to borontrifluoride-etherate-mediated reactions with one silyl ketene acetal and four silyl enol ethers. Reactions of primary and secondary amides did not lead to the desired CCbond formation. Reactions of the tertiary N,N-dimethylamide gave the expected γ-oxo-α-aminocarboxamides. The reaction of an N-methoxy-N-trimethylsilylcarboxamide with the ketene acetal also
为了开发方便的合成γ-氧代-α-氨基羧酰胺的方法,将五种不同的α-(烷氧基羰基)氨基-α-甲氧基乙酰胺与三氟硼化硼酸乙酯介导的反应与一种甲硅烷基乙烯酮缩醛和四种甲硅烷基烯醇醚进行了反应。伯酰胺和仲酰胺的反应未导致所需的C C键形成。N,N-二甲基酰胺叔胺的反应给出了预期的γ-氧代-α-氨基羧酰胺。一个的反应Ñ甲氧基Ñ -trimethylsilylcarboxamide与乙烯酮缩二醇也正常进行。但是,后者酰胺与甲硅烷基烯醇醚的初始产物分别通过环化进一步反应,得到环状的N-甲氧基-N-酰基中间体。根据所使用的烯醇醚的结构特征,这亚胺中间遭受任一质子损失和异构化,得到保护的3-氨基-1-甲氧基δ 3 -吡咯啉-2-酮,或进行与该烯醇醚,得到的第二联接保护的3-氨基-1-甲氧基吡咯烷二-2-酮。