Palladium-Catalyzed Intramolecular Hydroamination of Propargylic Carbamates and Carbamothioates
作者:Santosh Kumar Alamsetti、Andreas K. Å. Persson、Jan-E. Bäckvall
DOI:10.1021/ol5002279
日期:2014.3.7
An efficient and simple methodology was developed for the synthesis of oxazolidinones, oxazolidinthiones, imidazolidinthiones, and imidazolidinones from the corresponding propargylic starting materials using Pd(OAc)2 and n-Bu4NOAc as catalysts in DCE at room temperature.
开发了一种有效且简单的方法,用于在室温下在DCE中使用Pd(OAc)2和n- Bu 4 NOAc作为催化剂,从相应的炔丙基原料合成恶唑烷酮,恶唑烷硫酮,咪唑烷硫酮和咪唑烷酮。
Efficient 1,3‐Oxazolidin‐2‐one Synthesis through Heterogeneous Pd
<sup>II</sup>
‐Catalyzed Intramolecular Hydroamination of Propargylic Carbamates
Herein, we present an operationally simple protocol for the cycloisomerization of propargylic carbamates in which a heterogeneous catalyst consisting of Pd species immobilized on amino‐functionalized siliceous mesocellular foam (PdII‐AmP‐MCF) is used. This Pd nanocatalyst displayed high efficiency at low catalyst loading and reaction temperatures, which allowed for the efficient and mild synthesis
在此,我们提出了一种炔丙基氨基甲酸酯环异构化的操作简单协议,其中使用了由固定在氨基官能化硅质介孔泡沫(Pd II -AmP-MCF)上的Pd组成的非均相催化剂。这种Pd纳米催化剂在较低的催化剂负载量和反应温度下显示出高效率,从而可以高效,温和地合成各种1,3-恶唑烷酮-2-酮衍生物和相关化合物。此外,尽管在随后的循环中观察到活性逐渐下降,但事实证明,可以将Pd纳米催化剂再用于一些反应。
Palladium-Catalyzed Synthesis of Stereodefined 4-Arylidene-3 Tosyloxazolidin-2-ones from 2-Propynyl Tosylcarbamates and Unsaturated Halides (or Triflate)
2-propynyl tosylcarbamates undergo cyclisation-coupling reactions with aryl iodides (and one alkenyl triflate) in the presence of base and of catalytic amounts of a palladium(0)-phosphine complex to form (E)-4-arylidene or 4-alkylidene-3-tosyloxazolidin-2-ones in a regio- and stereoselective manner.
On treatment with catalytic amounts of gold(I) chloride (AuCl) and a base co-catalyst, O-propargyl carbamates smoothly undergo a 5-exo-dig cyclization at room temperature to afford 4-methylene-2-oxazolidinones in high yield. Substrates with a substituent at the alkyne terminus stereoselectively give rise to (Z)-4-alkylidene-2-oxazolidinones.
Copper(II)‐Catalyzed Aminohalogenation of Alkynyl Carbamates
作者:Sabrina Giofrè、Camilla Loro、Letizia Molteni、Carlo Castellano、Alessandro Contini、Donatella Nava、Gianluigi Broggini、Egle M. Beccalli
DOI:10.1002/ejoc.202100202
日期:2021.3.19
The aminohalogenation reaction of O‐alkynyl carbamates under copper catalysis has been developed. The intramolecular C−N bond formation occurs selectively affording haloalkylidene substituted heterocycles. In the case of α,α‐cyclohexyl‐substituted propargyl carbamate, the alkoxyhalogenation pathway was operative. The mechanism for the two alternative reaction pathways was investigated by modeling the