Highly Enantioselective Pictet-Spengler Reactions with α-Ketoamide-Derived Ketimines: Access to an Unusual Class of Quaternary α-Amino Amides
作者:Farhan R. Bou-Hamdan、James L. Leighton
DOI:10.1002/anie.200806110
日期:2009.3.16
story? N‐Aryl amides are effective directing/activating groups for chlorosilane Lewis acids. This aspect has been exploited for the development of the first simple and general method for the highlyenantioselective Pictet–Spengler reaction of ketimines derived from α‐ketoamides leading to quaternary α‐aminoacid derivatives (see scheme).
An efficient iodine-mediatedoxidation reaction for ynamides has been developed to produce N-monosubstituted α-ketoamides and α-ketoimides. This oxidative method, which exhibits good functional group tolerance, was performed under mild conditions without a metal catalyst.
Chemoselective hydrogenation of α,β-epoxy ketones and α-ketoamides is achieved at room temperature (25 °C) using 2.0 bar H2 and a pincer-ligated Mn(I) catalyst that provides synthetically valuable α-hydroxy epoxides and α-hydroxy amides. This protocol applies to a wide range of alkyl and aryl-substituted α,β-epoxy ketones, including terpenes (α-ionone, nootkatone, and R-carvone)- and steroids (testosterone
使用 2.0 bar H 2和钳式连接的 Mn(I) 催化剂在室温 (25 °C) 下实现 α,β-环氧酮和 α-酮酰胺的化学选择性氢化,从而提供具有合成价值的 α-羟基环氧化物和 α-羟基酰胺。该方案适用于各种烷基和芳基取代的 α,β-环氧酮,包括萜烯(α-紫罗兰酮、nootkatone 和 R-香芹酮)和类固醇(睾酮和黄体酮)衍生的环氧酮,并且耐受 H 2敏感官能团,如卤化物、乙酰基、腈基、硝基、环氧基、烯基和炔基。此外,带有可还原官能团(包括乙酰基和重氮苯)的α-酮酰胺在此方案下未受影响,并选择性地转化为α-羟基酰胺。初步的机理研究强调了金属-配体协同H 2活化过程。