A Dual Gold-Iron Catalysis for a One-Pot Synthesis of 2,3-Dihydroisoxazoles from Propargylic Alcohols and N-Protected Hydroxylamines
作者:Olivier Debleds、Christophe Dal Zotto、Emmanuel Vrancken、Jean-Marc Campagne、Pascal Retailleau
DOI:10.1002/adsc.200900127
日期:——
A concise one-pot route for the synthesis of 2,3-dihydroisoxazoles via a dual gold-iron catalysis has been devised. The method, based on the addition of binucleophilic protected hydroxylamine to propargylic alcohols, enables a one-pot, highly selective synthesis of these heterocycles (10 examples, up to 86% yield).
Pd(II)-catalyzed ligand-controlled switching between cyclization-carbonylation and cyclization-carbonylation-cyclization-coupling (CCC-coupling) reactions of propargylic N-hydroxylamines was investigated. The use of a [Pd(tfa)2(box)] catalyst in MeOH afforded symmetric ketones bearing two 2,3-dihydroisoxazoles in good yields; replacing the catalyst and solvent with Pd(tfa)(2) and MeOH/DMSO led to the formation of methyl 2,3-dihydroisoxazole-4-carboxylates in good yields.
Transition-Metal-Catalyzed Uninterrupted Four-Step Sequence to Access Trisubstituted Isoxazoles
We describe herein a novel uninterrupted four-step sequence to access trisubstituted isoxazoles from readily available propargylic alcohols using sequentially iron and palladium catalytic systems. The advantages of such a strategy are illustrated by the high overall yields and the time-saving procedure that are reported.
Stereoselective and Catalytic Access to β-Enaminones: An Entry to Pyrimidines
We describe herein a highly stereoselective access to Cbz-protected β-enaminones 2 based on the NaOH catalyzed rearrangement of propargylichydroxylamines 1. The synthetic potential of these β-enaminones is illustrated in an original synthesis of pyrimidines.
Straightforward synthesis of various chiral pyrimidines bearing a stereogenic center adjacent to the C-2 position, including C-terminal peptide isosteres
作者:Sami Sahtel、Chayma Ben Maamer、Rafâa Besbes、Emmanuel Vrancken、Jean-Marc Campagne
DOI:10.1007/s00726-022-03192-y
日期:2022.11
Boc-AA-NH2 and β-enaminones. This strategy allows the synthesis of a large variety of chiral pyrimidines (18 examples) with good yields from the chiral pool. In the case of peptide isosteres, this procedure proved to be highly stereoretentive and paves the way to the construction of C-terminal modified peptidomimetics as illustrated in the synthesis of two original pyrimidines containing pseudo-dipeptides
本研究描述了从现成的 Boc-AA-NH 2和 β-烯胺酮中有效获取对映体富集的嘧啶衍生物的方法。该策略允许从手性池中以良好的收率合成多种手性嘧啶(18 个例子)。在肽等排物的情况下,该程序被证明具有高度立体保留性,并为构建 C 末端修饰的肽模拟物铺平了道路,如两个含有假二肽的原始嘧啶的合成所示。