Diphenylparabanic Acid as a Synthon for the Synthesis of α-Diketones and α-Ketocarboxylic Acids
作者:Nobuko Watanabe、Mitsutaka Hamano、Shota Todaka、Takahiro Asaeda、Hisako K. Ijuin、Masakatsu Matsumoto
DOI:10.1021/jo202304x
日期:2012.1.6
Diphenylparabanic acid was found to react with >2 equiv of organolithiums at −78 °C to effectively give the corresponding symmetrical α-diketones. However, upon treatment with 1 equiv of organolithium, the parabanic acid gave mainly 5-substituted 5-hydroxyimidazolidine-2,4-diones. On the other hand, Grignard reagents were less reactive toward the parabanic acid at low temperature, and selectively gave
发现二苯基对羟基苯甲酸在-78°C下与> 2当量的有机锂反应,可以有效地产生相应的对称α-二酮。然而,用1当量的有机锂处理后,对羟基苯甲酸主要产生5-取代的5-羟基咪唑烷-2,4-二酮。另一方面,即使使用多于1当量的试剂,格氏试剂在低温下对对羟基苯甲酸的反应性较小,并选择性地得到相应的5-羟基咪唑烷-2,4-二酮。串联过程中,首先将对羟基苯甲酸与格氏试剂反应,然后与有机锂一锅反应,有效地得到了不对称的α-二酮。5-取代的5-羟基咪唑烷-2,4-二酮可用作制备α-酮羧酸以及不对称α-二酮的通用前体。