Synthesis of Fmoc-Protected Amino Alcohols via the Sharpless Asymmetric Aminohydroxylation Reaction Using FmocNHCl as the Nitrogen Source
作者:Ryan Moreira、Matthew Diamandas、Scott D. Taylor
DOI:10.1021/acs.joc.9b02491
日期:2019.12.6
The aminohydroxylation of various alkenes using FmocNHCl as a nitrogen source is reported. In general, in the absence of a ligand, the reaction provided racemic Fmoc-protected amino alcohols with excellent regioselectivity but in low to moderate yields. However, in some instances, the yield of an amino alcohol product and the regioselectivity could be altered by the addition of a catalytic amount of
报道了使用FmocNHCl作为氮源的各种烯烃的氨基羟基化。通常,在不存在配体的情况下,该反应提供了外消旋的Fmoc保护的氨基醇,具有优异的区域选择性,但产率低至中等。但是,在某些情况下,可以通过添加催化量的三乙胺(TEA)来改变氨基醇产物的产率和区域选择性。使用(DHQD)2 PHAL(DHQD)或(DHQ)2进行此反应的Sharpless不对称变体(Sharpless不对称氨基羟基化(SAAH))与没有手性配体的相同反应相比,作为手性配体的PHAL(DHQ)更容易进行且收率更高。除两个实施例外,所有实施例的对映体比率(er)均超过90:10,许多实施例的er值均达到95:5或更高,这使得FmocNHCl成为制备手性氨基醇的高度实用的试剂。采用使用FmocNHCl的SAAH反应用于制备d -苏-β-hydroxyasparagine和d -苏-β-methoxyaspartate,对于Fmoc固相肽合成适当保护的。