Methods for the Synthesis of 5,6,7,8-Tetrahydro-1,8-naphthyridine Fragments for αVβ3 Integrin Antagonists
摘要:
The preparation of 3-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)propan-1-amine 2a and 3-[(7R)-7-methyl-5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl]propan-1-amine 2b, key intermediates in the synthesis of alpha(V)beta(3) antagonists, is described. The syntheses rely on the efficient double Sonogashira reactions of 2,5-dibromopyridine 3 with acetylenic alcohols 4a/4b and protected propargylamines 10a-e followed by Chichibabin cyclizations of 3,3'-pyridine-2,5-diyldipropan-1-amines 9a/9b.
A substituent- and temperature-controllable NHC-derived zwitterionic catalyst enables CO<sub>2</sub> upgrading for high-efficiency construction of formamides and benzimidazoles
作者:Zhaozhuo Yu、Zhengyi Li、Lilong Zhang、Kaixun Zhu、Hongguo Wu、Hu Li、Song Yang
DOI:10.1039/d1gc01897c
日期:——
zwitterionic catalyst for efficient CO2 reductive upgrading via either N-formylation or further coupling with cyclization under mild conditions (25 °C, 1 atm CO2) using hydrosilane as a hydrogen source. More than 30 different alkyl and aromatic amines could be transformed into the corresponding formamides or benzimidazoles with remarkable yields (74%–98%). The electronic effect of the introduced substituent
近年来,将温室气体CO 2化学催化升级为有价值的化学品和生物燃料引起了广泛关注。在已报道的方法中,CO 2与胺的N-甲酰化由于其在构建含N 线性和环状骨架方面的多功能性而具有重要意义。这里,稳定的N-杂环卡宾-羧基加合物(NHC-CO 2)中制备的轻便和可作为用于高效CO可回收两性离子催化剂2还原升级经由任一Ñ -formylation或另外的耦合用温和的条件下环化(25 °C, 1 atm CO 2) 使用氢硅烷作为氢源。超过 30 种不同的烷基和芳香胺可以转化为相应的甲酰胺或苯并咪唑,产率显着(74%–98%)。发现引入的取代基对NHC-CO 2的电子效应明显影响两性离子催化剂的热稳定性和亲核性,这与其催化活性直接相关。此外,NHC-CO 2可以通过在特定温度下原位脱羧来提供CO 2,这取决于引入的取代基类型。实验和计算研究表明,NHC-CO 2上的羧基物质不仅是亲核中心,而且还是在氢化硅烷化过程中快速捕获或替代环境
Facile access to <i>N</i>-formyl imide as an <i>N</i>-formylating agent for the direct synthesis of <i>N</i>-formamides, benzimidazoles and quinazolinones
N-Formamide synthesis using N-formyl imide with primary and secondary amines with catalytic amounts of p-toluenesulfonic acid monohydrate (TsOH·H2O) is described. This reaction is performed in water without the use of surfactants. Moreover, N-formyl imide is efficiently synthesized using acylamidines with TsOH·H2O in water. In addition, N-formyl imide was successfully used as a carbonyl source in the
Herein, we report a sustainable approach for N-formylation of aromatic as well as aliphaticamines using sodium borohydride and carbon dioxide gas. The developed approach is catalyst free, and does not need pressure or a specialized reaction assembly. The reductive formylation of CO2 with sodium borohydride generates formoxy borohydride species in situ, as confirmed by 1H and 11B NMR spectroscopy.
A novel chitosan-catalyzed transamidation of carboxamides with amines under solvent-free conditions is described. A series of amide derivatives as well as more challenging aryl and alkyl amines with long-chain alkyl substituents could be selectively converted into the corresponding transamidation products, which are frequently found in biologically active compounds and pharmaceuticals. Under similar reaction conditions benzo[d]heterocycles were also obtained via a one-pot synthesis through transamidation and subsequent dehydration. Recyclability of chitosan was demonstrated, with quantitative yields of products obtained without any loss of catalytic activity.
A NHC-Silyliumylidene Cation for Catalytic <i>N</i>-Formylation of Amines Using Carbon Dioxide
作者:Bi-Xiang Leong、Yeow-Chuan Teo、Cloé Condamines、Ming-Chung Yang、Ming-Der Su、Cheuk-Wai So
DOI:10.1021/acscatal.0c03795
日期:2020.12.18
This study describes the use of a silicon(II) complex, namely, the NHC-silyliumylidene cation complex [(IMe)2SiH]I (1, IMe = :CN(Me)C(Me)}2), to catalyze the chemoselective N-formylation of primary and secondary aminesusing CO2 and PhSiH3 under mild conditions to afford the corresponding formamides as a sole product (average reaction time: 4.5 h; primary amines, average yield: 95%, average TOF: 8
这项研究描述了硅(II)配合物的使用,即NHC-亚甲硅烷基阳离子配合物[(I Me)2 SiH] I(1,I Me =:C N(Me)C(Me)} 2) ,以在温和条件下使用CO 2和PhSiH 3催化伯胺和仲胺的化学选择性N-甲酰化,以提供相应的甲酰胺为唯一产物(平均反应时间:4.5小时;伯胺,平均收率:95%,平均TOF :8 h –1;仲胺,平均收率:98%,平均TOF:17 h –1)。活动1产品收率优于目前用于该催化的非过渡金属催化剂。机理研究表明,与非过渡金属催化剂相比,配合物1中的硅(II)中心通过不同的途径催化C–N键的形成。它依次激活CO 2,PhSiH 3和胺,这些胺通过二氢消除机理进行反应,形成甲酰胺,硅氧烷和二氢气体。