The reaction of various alpha-silyl-alpha-keto esters with thiosemicarbazide at 50 degrees C in ethyl acetate was found to give alpha-silyl-substituted thiosemicarbazone-acetic acid esters in good yield. These may then be converted to their corresponding silyl-substituted 1,2,4-triazin-5-ones by cyclization under basic conditions. (c) 2005 Elsevier Ltd. All rights reserved.
Synthesis and Use of α-Silyl-Substituted α-Hydroxyacetic Acids
摘要:
Rhodium-catalyzed oxygen transfer was used to generate benzyl 2-sifyi-2-oxoacetates in good yields. The hydrogenation of these compounds led to chiral alpha-silyl-substituted a-hydroxyacetic acids. Resolution by means of HPLC using a chiral stationary phase afforded an enantiomerically pure representative of this class of compounds, which was successfully applied as a chiral ligand in an asymmetric aldol-type reaction.