Silver(I)-promoted asymmetric halomethoxylation of chiral α,β-unsaturated carboxylic acid derivatives: enantioselective synthesis of N-protected syn-β-methoxy-α-amino acids
作者:Saumen Hajra、Ananta Karmakar、Manishabrata Bhowmick
DOI:10.1016/j.tetasy.2005.12.014
日期:2006.1
Asymmetric halomethoxylation of chiral α,β-unsaturated carboxylic acid derivatives was performed with halogens (Br2/I2) promoted by silver(I) salts with high regio- and anti-selectivity and moderate to good diastereoselectivity. Reagent controlled diastereoselectivity was observed for N-cinnamoyl-2-oxazolidinone substrates especially for cinnamoyl and electron-deficient cinnamoyl substrates, when Ag2O
手性α,β-不饱和羧酸衍生物的不对称卤甲氧基化反应,是由银(I)盐促进的卤素(Br 2 / I 2)具有较高的区域选择性和抗选择性,并且具有中等至良好的非对映选择性。当使用Ag 2 O代替AgNO 3作为促进剂时,对于N-肉桂酰基-2-恶唑烷酮底物,尤其是肉桂酰基和电子缺陷型肉桂酰基底物,观察到了试剂控制的非对映选择性。包含Oppolzer的sultam手性助剂的Enoyl底物独立于Ag(I)盐的抗衡离子。该方法用于N-保护的顺式的两种对映体的短合成-β-甲氧基苯基丙氨酸以及N和O保护的顺式-β-甲氧基酪氨酸,它们是具有生物活性的环肽和去污肽抗生素的不常见氨基酸成分。