Use of the SPhos Ligand to Suppress Racemization in Arylpinacolboronate Ester Suzuki Couplings Involving α-Amino Acids. Synthesis of Biaryl Derivatives of 4-Hydroxyphenylglycine, Tyrosine, and Tryptophan
作者:Mònica Prieto、Silvia Mayor、Paul Lloyd-Williams、Ernest Giralt
DOI:10.1021/jo901899w
日期:2009.12.4
α-Amino acid derivatives, particularly those of phenylglycine, can suffer significant racemization in Suzuki couplings. When arylpinacolboronate esters are used as coupling partners this unwanted side reaction can be suppressed by the use of Pd(OAc)2 as Pd(0) source, in the presence of Buchwald’s SPhos ligand. The syntheses of biaryl amino acids of tyrosine, phenylglycine, and tryptophan, including
α-氨基酸衍生物,特别是苯基甘氨酸的衍生物,在Suzuki偶联中会遭受显着的消旋作用。当芳基频哪醇硼酸酯用作偶联伙伴时,在存在布赫瓦尔德氏SPhos配体的情况下,可以通过使用Pd(OAc)2作为Pd(0)来抑制这种有害的副反应。据报道,酪氨酸,苯基甘氨酸和色氨酸的联芳基氨基酸的合成,包括与天然肽中的氯肽家族相似的Phg-Trp单元。