Synthesis of Quaternary-Carbon-Containing β^2,2-Amino Acids by the Rh^I-Catalyzed Enantioselective Arylation of α-Substituted β-Nitroacrylates

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• 作者：Jo-Hsuan Fang ; Jia-Hong Jian ; Dr. Hao-Ching Chang ; Ting-Shen Kuo ; Prof. Dr. Way-Zen Lee ; Dr. Ping-Yu Wu and Prof. Dr. Hsyueh-Liang Wu
• 刊名：Chemistry - A European Journal
• 出版年：2017
• 出版时间：February 3, 2017
• 年：2017
• 卷：23
• 期：8
• 页码：1830-1838
• 全文大小：1005K
• ISSN：1521-3765

文摘

An enantioselective Rh^I-catalyzed conjugate addition reaction of α-substituted β-nitroacrylates with various arylboronic acids by using chiral Rh^I diene catalysts is described for the first time. The addition reaction proceeds under mild conditions in a range of common organic solvents and additives, and it affords the corresponding quaternary-carbon-containing α,α-disubstituted β-nitropropionate products in up to 63 % yield and 99 % ee. Reaction of either (E)- or (Z)-β-nitroacrylates provided the same enantiomer of the product, and a range of esters and aryl groups were tolerated. To demonstrate the utility of the method, ethyl (R)-1,1-methyl-1-phenyl-3-nitropropionate, prepared herein, was converted to the non-proteinogenic β^2,2-amino acid, (R)-2-(aminomethyl)-2-phenylpropanoic acid, and to the β^2,2-lactam, (R)-3-methyl-3-phenylazetidin-2-one. In addition, a tripeptide, which comprised l-phenylalanine, l-alanine, and β^2,2-amino acid 7, was also synthesized.