A synthesis of optically active alpha-quaternary alpha-amino acids and esters by assembling three components, ketones, (R)-chloromethyl p-tolyl sulfoxide, and sodium azide, via sulfinyloxiranes

作者：Satoh Tsuyoshi^*; Hirano Mizue; Kuroiwa Akio; Kaneko Youhei

来源：Tetrahedron, 2006, 62(39): 9268-9279.

DOI：10.1016/j.tet.2006.06.112

• alpha-amino acid
• alpha-quaternary alpha-amino acid
• cyclic alpha-amino acid
• sulfinyloxirane
• asymmetric synthesis

Treatment of lithium alpha-sulfinyl carbanion of chloromethyl p-tolyl sulfoxides with ketones at low temperature afforded adducts in almost quantitative yields, which were exposed to t-BuOK to give sulfinyloxiranes in high yields. The sulfinyloxirane was reacted with benzylamine to give alpha-amino aldehyde, which was oxidized with iodine in methanol to afford alpha-amino carboxylic ester in moderate yield. The sulfinyloxiranes were treated with sodium azide to afford alpha-azido aldehydes in good yields. Oxidation with NaClO2 followed by catalytic hydrogenation of the azido group of the alpha-azido aldehydes gave alpha-quaternary alpha-amino acids in good overall yields. The oxidation of the azido aldehydes with iodine in methanol in the presence of KOH followed by the catalytic hydrogenation resulted in alpha-quaternary alpha-amino acid methyl esters in good yields. When these reactions were carried out starting from unsymmetrical ketones and optically pure (R)-chloromethyl p-tolyl sulfoxide, a new method for a synthesis of optically active alpha-quaternary alpha-amino acids and esters in good overall yields was realized.

• 出版日期2006-9-25