Oxidative Homocoupling of Chiral 3-Arylpropanoic Acid Derivatives. Application to Asymmetric Synthesis of Lignans
作者:Naoki Kise、Takako Ueda、Kimikage Kumada、Yuichi Terao、Nasuo Ueda
DOI:10.1021/jo991317o
日期:2000.1.1
TiCl(4), PhI(OAc)(2), or CuCl(2) as an oxidant. The stereoselectivity can be explained by a radical coupling mechanism. Optically active dibenzylbutyrolactone lignans, such as (-)-hinokinin and (-)-dimethylmatairesinol, and dibenzylbutanediol lignans, such as (-)-dihydrocubebin and (-)-dimethylsecoisolariciresinol, were synthesized from the major R,R-dimers. The oxidative coupling of (4R, 5S)-1-(3-arylpropanoyl)-3
(4S)-3-(3-芳基丙酰基)-4-异丙基-2-恶唑烷酮和(4R,5S)-1-(3-芳基丙酰基)-3,4-二甲基-5-苯基的烯醇锂的氧化均偶联-2-咪唑啉酮类化合物以TiCl(4),PhI(OAc)(2)或CuCl(2)为氧化剂立体选择性地给出了相应的R,R-二聚体。立体选择性可以通过自由基偶联机理来解释。由主要的R,R-二聚体合成了光学活性的二苄基丁内酯木脂素,例如(-)-激肽和(-)-二甲基麦角甾醇,和二苄基丁二醇木脂素,例如(-)-二氢立方体素和(-)-二甲基-异异二十二烯醇。(4R,5S)-1-(3-芳基丙酰基)-3,4-二甲基-5-苯基-2-咪唑啉酮与LDA-I(2)的氧化偶合主要得到R,S-二聚体,该结果可以用S(N)2机制来解释。