Asymmetric Friedel–Crafts alkylation of activated benzenes with methyl (E)-2-oxo-4-aryl-3-butenoates catalyzed by [Pybox/Sc(OTf)3]
摘要:
The asymmetric Friedel-Crafts reaction between methyl (E)-2-oxo-4-aryl-3-butenoates (la-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. (C) 2010 Elsevier Ltd. All rights reserved.
Asymmetric Friedel–Crafts alkylation of activated benzenes with methyl (E)-2-oxo-4-aryl-3-butenoates catalyzed by [Pybox/Sc(OTf)3]
摘要:
The asymmetric Friedel-Crafts reaction between methyl (E)-2-oxo-4-aryl-3-butenoates (la-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. (C) 2010 Elsevier Ltd. All rights reserved.