N,O Highly Regio- and Stereoselective Alkylation of Nucleophilic Glycine Equivalents with Carbonates of Allylic α-Hydroxyphosphonates: A Convenient Route to Racemic 2-Amino-5-phosphono-4-pentenoic Acids
作者:Elisabeth Öhler、Silvia Kanzler
DOI:10.1002/jlac.199719970722
日期:1997.7
Palladium(0)-catalyzed allylic alkylation of diethyl (acetyl-amino)malonate (6), ethyl (diphenylmethyleneamino)acetate (7), and (diphenylmethyleneamino)acetonitrile (8), respectively, with the acrolein-derived 1-dialkoxyphosphinyl-substituted carbonates 5 provides the γ-substituted vinylphosphonates 9–11 in very good yields and with high regioselectivity. The stereochemical outcome is dependent on
钯(0)催化(乙酰氨基氨基)丙二酸二乙酯(6),乙基(二苯基亚甲基氨基)乙酸乙酯(7)和(二苯基亚甲基氨基)乙腈(8)与丙烯醛衍生的1-二烷氧基膦基取代的烯丙基烷基化碳酸盐5以非常好的收率和较高的区域选择性提供γ-取代的乙烯基膦酸盐9-11。立体化学结果取决于甘氨酸等效物6-8的亲核活化方式:当在N,O-双(三甲基甲硅烷基)乙酰胺(BSA)存在下进行反应时,(Z)异构体(Z)-9 –(Z)-11非常受青睐,而在不存在亲核试剂的任何其他活化的情况下,相应的(E)异构体占主导地位。在后一种情况下,在席夫碱衍生物7和8烷基化时,分别分离出高达30%的α-取代产物12和13作为副产物。乙烯基膦酸酯9-11容易转化为外消旋的2-氨基-5-膦基-4-戊烯酸(Z)-3和(E)-3,以及饱和的类似物1。