Asymmetric Friedel–Crafts alkylation of activated benzenes with methyl (E)-2-oxo-4-aryl-3-butenoates catalyzed by [Pybox/Sc(OTf)₃]

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• 作者：Giuseppe Faita ; Mariella Mella ; Marco Toscanini ; Giovanni Desimoni
• 关键词：Asymmetric catalysis ; Friedel– ; Crafts reaction ; Enantioselectivity ; PYBOX ligand ; Scandium triflate
• 刊名：Tetrahedron
• 出版年：2010
• 出版时间：17 April 2010
• 年：2010
• 卷：66
• 期：16
• 页码：3024-3029
• 全文大小：282 K

文摘

The asymmetric Friedel–Crafts reaction between methyl (E)-2-oxo-4-aryl-3-butenoates (1a–c) and activated benzenes (2a–d) has been efficiently catalyzed by the Sc^III triflate complex of (4′S,5′S)-2,6-bis[4′-(triisopropylsilyl) oxymethyl-5′-phenyl-1′,3′-oxazolin-2′-yl]pyridine (pybox 3). The 4,4-diaryl-2-oxo-butyric acid methyl esters (4) are usually formed in good yields and the enantioselectivity is up to 99 % ee. The sense of the stereoinduction can be rationalized with the same octahedral complex (10) between 1, pybox 3 and Sc triflate already proposed for other reactions involving pyruvates, and catalyzed by the same complex.