Selective Michael−Aldol Reaction by Use of Sterically Hindered Aluminum Aryloxides as Lewis Acids: An Easy Approach to Cyclobutane Amino Acids
作者:Alberto Avenoza、Jesús H. Busto、Noelia Canal、Jesús M. Peregrina、Marta Pérez-Fernández
DOI:10.1021/ol0514707
日期:2005.8.1
cycloaddition of 2-amidoacrylates with monosubstituted donor olefins, including its asymmetric version, is described. The stereoselectivity of this reaction can be modulated by the use of sterically hindered aluminum aryloxides or methylaluminoxane as Lewis acids. The reaction was applied to the synthesis of both stereoisomers of 2-benzyloxycyclobutane-alpha-amino acid, which are protected serine analogues c(4)Ser(OBn)
描述了2-酰胺基丙烯酸酯与单取代的供体烯烃的正式[2 + 2]环加成反应,包括其不对称形式。该反应的立体选择性可以通过使用空间受阻的芳基氧化铝或甲基铝氧烷作为路易斯酸来调节。该反应应用于2-苄氧基环丁烷-α-氨基酸的两种立体异构体的合成,它们是受保护的丝氨酸类似物c(4)Ser(OBn)。