Synthesis of (optically active) sulfur-containing trifunctional amino acids by radical addition to (optically active) unsaturated amino acids
摘要:
Sulfur-based radicals, generated from R-S-H-type precursors (R = alkyl, acyl) with AIBN, smoothly add to alpha-allylglycines protected at none, one, or both of the amino acid functions (NH2 and/or CO2H). Sulfur-containing trifunctional amino acids were obtained in good to excellent yields (64-100%). The solvent used for the reaction is critical. Optimal results were obtained when both the unsaturated amino acid and RSH dissolve completely in the medium (dioxane/water or methanol/water are good solvent systems). The scope of the reaction includes alpha-substituted alpha-allylglycine and derivatives as well as beta-substituted beta-allyl-beta-ammo alcohols. In the case of optically active alpha-allylglycine derivatives, radical addition is accompanied by a small amount of racemization, the amount depending on the type of protection and R-S-H. The products are easily optically enriched by crystallization. Addition of sulfur-based radicals to alpha-allylglycine is believed to be an example of a general method for synthesizing optically active trifunctional amino acids from unsaturated amino acids.
Synthesis of Thiol-Containing Amino Acids Through Alkylation of Glycinate Ketimine
作者:Jian Zhi、Yuli Xiao、Aiguo Hu
DOI:10.1080/00397911.2010.533803
日期:2012.3.15
Abstract A general synthetic route for the synthesis of thiol-containing amino acids through alkylation of glycinate ketimine followed by hydrolysis was developed in this work. The common problems associated with the instability of ketimines and thioesters were solved by optimization of both synthetic and purification conditions. A series of thiol-containing amino acids were obtained in good yields. This method