Diastereoselective alkylation of chiral 2-imidazolidinone glycolates: asymmetric synthesis of α-hydroxy carboxylic acids

Highly Diastereoselective α-Hydroxylation of Fox Chiral Auxiliary-Based Amide Enolates with Molecular Oxygen

“…Moreover, the reaction turned out to be completely diastereoselective (>98% de) with more sterically hindered enolates (Table , entries 2 and 3). In these experiments, no trace of the minor diastereomer could be detected by 19 F and 1 H NMR in the crude reaction mixture . The oxidation of the highly hindered tert -butyl substrate 1d was achieved in reasonable yield without loss of stereoselectivity provided that the temperature was raised to −50 °C (Table , entry 4).…”

Asymmetric Glycolate Alkylation Reactions in the Solid Phase Using 2-Imidazolidinone Chiral Auxiliary

“…As compared to the same model reactions in the solution phase, 5 the asymmetric glycolate alkylation reactions in the solid phase were more difficult to perform and required a higher temperature. The lithium enolate generated by LDA appeared optimal in most cases of the solid phase reactions.…”

“…4 The 2-imidazolidinone chiral auxiliary also exhibited high stereoselectivities in asymmetric glycolate alkylation reactions in the solution phase for the synthesis of chiral benzyl protected α-hydroxy carboxylic acids as important synthetic building blocks. 5 Herein, we wish to report the application of the solid supported 2-imidazolidinone chiral auxiliary to asymmetric glycolate alkylation reactions. To the best of our knowledge, this type of reaction has not been explored in the solid phase so far.…”