Asymmetric Michael reaction between a chiral α,β-dimethyl-β-enamino ester and α-substituted acrylates
摘要:
An asymmetric Michael reaction between a chiral alpha,beta-dimethyl-beta-enamino ester derived from (S)-1-phenylethylamine and alpha-substituted acrylates is reported. Methyl acetamidoacrylate and methyl acetoxyacrylate furnished the expected Michael adduct with good ee's and de's. By contrast, an annulation process of the intermediary imine took place when using methyl methacrylates. (C) 2004 Elsevier Ltd. All rights reserved.
In contrast with keto diester (R)-10a bearing a methyl ester group at the quaternary carbon center, the benzyl ester analogue (R)-10a partially racemized during workup, thereby revealing that the nature of the ester group at the quaternary carbon center has a critical role in the rate of racemization of such Michael adducts. (c) 2005 Elsevier Ltd. All rights reserved.
An asymmetric Michael reaction between a chiral alpha,beta-dimethyl-beta-enamino ester derived from (S)-1-phenylethylamine and alpha-substituted acrylates is reported. Methyl acetamidoacrylate and methyl acetoxyacrylate furnished the expected Michael adduct with good ee's and de's. By contrast, an annulation process of the intermediary imine took place when using methyl methacrylates. (C) 2004 Elsevier Ltd. All rights reserved.